重构: 将 LogCleanupService 转为 Quartz Job 服务

- 创建 LogCleanupJob 替代 LogCleanupService (BackgroundService)
- 在 Expand.cs 中注册 LogCleanupJob (每天凌晨2点执行, 保留30天日志)
- 从 Program.cs 移除 LogCleanupService 的 HostedService 注册
- 删除 Service/LogCleanupService.cs
- 删除 Service/PeriodicBillBackgroundService.cs (已无用的重复服务)

所有后台任务现在统一通过 Quartz.NET 管理, 支持运行时控制

Service/AI/OpenAiService.cs

@@ -0,0 +1,273 @@
+using System.Net.Http.Headers;
+
+namespace Service.AI;
+
+public interface IOpenAiService
+{
+    Task<string?> ChatAsync(string systemPrompt, string userPrompt);
+    Task<string?> ChatAsync(string prompt);
+    IAsyncEnumerable<string> ChatStreamAsync(string systemPrompt, string userPrompt);
+    IAsyncEnumerable<string> ChatStreamAsync(string prompt);
+}
+
+public class OpenAiService(
+    IOptions<AiSettings> aiSettings,
+    ILogger<OpenAiService> logger
+) : IOpenAiService
+{
+    public async Task<string?> ChatAsync(string systemPrompt, string userPrompt)
+    {
+        var cfg = aiSettings.Value;
+        if (string.IsNullOrWhiteSpace(cfg.Endpoint) || 
+            string.IsNullOrWhiteSpace(cfg.Key) || 
+            string.IsNullOrWhiteSpace(cfg.Model))
+        {
+            logger.LogWarning("未配置 OpenAI/DeepSeek 接口，无法调用 AI");
+            return null;
+        }
+
+        using var http = new HttpClient();
+        http.Timeout = TimeSpan.FromSeconds(15);
+        http.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", cfg.Key);
+
+        var payload = new
+        {
+            model = cfg.Model,
+            temperature = 0,
+            messages = new object[]
+            {
+                new { role = "system", content = systemPrompt },
+                new { role = "user", content = userPrompt }
+            }
+        };
+
+        var url = cfg.Endpoint.TrimEnd('/') + "/chat/completions";
+        var json = JsonSerializer.Serialize(payload);
+        using var content = new StringContent(json, Encoding.UTF8, "application/json");
+    
+        try
+        {
+            using var resp = await http.PostAsync(url, content);
+            if (!resp.IsSuccessStatusCode)
+            {
+                var err = await resp.Content.ReadAsStringAsync();
+                throw new InvalidOperationException($"AI接口调用失败: {(int)resp.StatusCode} {resp.ReasonPhrase}, {err}");
+            }
+
+            var respText = await resp.Content.ReadAsStringAsync();
+
+            using var doc = JsonDocument.Parse(respText);
+            var root = doc.RootElement;
+            var contentText = root.GetProperty("choices")[0]
+                .GetProperty("message")
+                .GetProperty("content")
+                .GetString();
+
+            return contentText;
+        }
+        catch (Exception ex)
+        {
+            logger.LogError(ex, "AI 调用失败");
+            throw;
+        }
+    }
+
+    public async Task<string?> ChatAsync(string prompt)
+    {
+        var cfg = aiSettings.Value;
+        if (string.IsNullOrWhiteSpace(cfg.Endpoint) || 
+            string.IsNullOrWhiteSpace(cfg.Key) || 
+            string.IsNullOrWhiteSpace(cfg.Model))
+        {
+            logger.LogWarning("未配置 OpenAI/DeepSeek 接口，无法调用 AI");
+            return null;
+        }
+
+        using var http = new HttpClient();
+        http.Timeout = TimeSpan.FromSeconds(60 * 5);
+        http.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", cfg.Key);
+
+        var payload = new
+        {
+            model = cfg.Model,
+            temperature = 0,
+            messages = new object[]
+            {
+                new { role = "user", content = prompt }
+            }
+        };
+
+        var url = cfg.Endpoint.TrimEnd('/') + "/chat/completions";
+        var json = JsonSerializer.Serialize(payload);
+        using var content = new StringContent(json, Encoding.UTF8, "application/json");
+    
+        try
+        {
+            using var resp = await http.PostAsync(url, content);
+            if (!resp.IsSuccessStatusCode)
+            {
+                var err = await resp.Content.ReadAsStringAsync();
+                throw new InvalidOperationException($"AI接口调用失败: {(int)resp.StatusCode} {resp.ReasonPhrase}, {err}");
+            }
+
+            var respText = await resp.Content.ReadAsStringAsync();
+
+            using var doc = JsonDocument.Parse(respText);
+            var root = doc.RootElement;
+            var contentText = root.GetProperty("choices")[0]
+                .GetProperty("message")
+                .GetProperty("content")
+                .GetString();
+
+            return contentText;
+        }
+        catch (Exception ex)
+        {
+            logger.LogError(ex, "AI 调用失败");
+            throw;
+        }
+    }
+
+    public async IAsyncEnumerable<string> ChatStreamAsync(string prompt)
+    {
+        var cfg = aiSettings.Value;
+        if (string.IsNullOrWhiteSpace(cfg.Endpoint) || 
+            string.IsNullOrWhiteSpace(cfg.Key) || 
+            string.IsNullOrWhiteSpace(cfg.Model))
+        {
+            logger.LogWarning("未配置 OpenAI/DeepSeek 接口，无法调用 AI");
+            yield break;
+        }
+
+        using var http = new HttpClient();
+        http.Timeout = TimeSpan.FromMinutes(5);
+        http.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", cfg.Key);
+
+        var payload = new
+        {
+            model = cfg.Model,
+            temperature = 0,
+            stream = true,
+            messages = new object[]
+            {
+                new { role = "user", content = prompt }
+            }
+        };
+
+        var url = cfg.Endpoint.TrimEnd('/') + "/chat/completions";
+        var json = JsonSerializer.Serialize(payload);
+        using var content = new StringContent(json, Encoding.UTF8, "application/json");
+    
+        using var request = new HttpRequestMessage(HttpMethod.Post, url);
+        request.Content = content;
+        using var resp = await http.SendAsync(request, HttpCompletionOption.ResponseHeadersRead);
+    
+        if (!resp.IsSuccessStatusCode)
+        {
+            var err = await resp.Content.ReadAsStringAsync();
+            throw new InvalidOperationException($"AI接口调用失败: {(int)resp.StatusCode} {resp.ReasonPhrase}, {err}");
+        }
+
+        using var stream = await resp.Content.ReadAsStreamAsync();
+        using var reader = new StreamReader(stream);
+
+        string? line;
+        while ((line = await reader.ReadLineAsync()) != null)
+        {
+            if (string.IsNullOrWhiteSpace(line) || !line.StartsWith("data: "))
+                continue;
+
+            var data = line.Substring(6).Trim();
+            if (data == "[DONE]")
+                break;
+
+            using var doc = JsonDocument.Parse(data);
+            var root = doc.RootElement;
+            if (root.TryGetProperty("choices", out var choices) && choices.GetArrayLength() > 0)
+            {
+                var delta = choices[0].GetProperty("delta");
+                if (delta.TryGetProperty("content", out var contentProp))
+                {
+                    var contentText = contentProp.GetString();
+                    if (!string.IsNullOrEmpty(contentText))
+                    {
+                        yield return contentText;
+                    }
+                }
+            }
+        }
+    }
+
+    public async IAsyncEnumerable<string> ChatStreamAsync(string systemPrompt, string userPrompt)
+    {
+        var cfg = aiSettings.Value;
+        if (string.IsNullOrWhiteSpace(cfg.Endpoint) || 
+            string.IsNullOrWhiteSpace(cfg.Key) || 
+            string.IsNullOrWhiteSpace(cfg.Model))
+        {
+            logger.LogWarning("未配置 OpenAI/DeepSeek 接口，无法调用 AI");
+            yield break;
+        }
+
+        using var http = new HttpClient();
+        http.Timeout = TimeSpan.FromMinutes(5);
+        http.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", cfg.Key);
+
+        var payload = new
+        {
+            model = cfg.Model,
+            temperature = 0,
+            stream = true,
+            messages = new object[]
+            {
+                new { role = "system", content = systemPrompt },
+                new { role = "user", content = userPrompt }
+            }
+        };
+
+        var url = cfg.Endpoint.TrimEnd('/') + "/chat/completions";
+        var json = JsonSerializer.Serialize(payload);
+        using var content = new StringContent(json, Encoding.UTF8, "application/json");
+    
+        // 使用 SendAsync 来支持 HttpCompletionOption
+        using var request = new HttpRequestMessage(HttpMethod.Post, url);
+        request.Content = content;
+        using var resp = await http.SendAsync(request, HttpCompletionOption.ResponseHeadersRead);
+    
+        if (!resp.IsSuccessStatusCode)
+        {
+            var err = await resp.Content.ReadAsStringAsync();
+            throw new InvalidOperationException($"AI接口调用失败: {(int)resp.StatusCode} {resp.ReasonPhrase}, {err}");
+        }
+
+        using var stream = await resp.Content.ReadAsStreamAsync();
+        using var reader = new StreamReader(stream);
+
+        string? line;
+        while ((line = await reader.ReadLineAsync()) != null)
+        {
+            if (string.IsNullOrWhiteSpace(line) || !line.StartsWith("data: "))
+                continue;
+
+            var data = line.Substring(6).Trim();
+            if (data == "[DONE]")
+                break;
+
+            // 解析JSON时不使用try-catch，因为在async iterator中不能使用
+            using var doc = JsonDocument.Parse(data);
+            var root = doc.RootElement;
+            if (root.TryGetProperty("choices", out var choices) && choices.GetArrayLength() > 0)
+            {
+                var delta = choices[0].GetProperty("delta");
+                if (delta.TryGetProperty("content", out var contentProp))
+                {
+                    var contentText = contentProp.GetString();
+                    if (!string.IsNullOrEmpty(contentText))
+                    {
+                        yield return contentText;
+                    }
+                }
+            }
+        }
+    }
+}