feat: 添加预算类别名称更新功能，优化相关控制器逻辑

Repository/BudgetRepository.cs

@@ -3,6 +3,8 @@
 public interface IBudgetRepository : IBaseRepository<BudgetRecord>
 {
     Task<decimal> GetCurrentAmountAsync(BudgetRecord budget, DateTime startDate, DateTime endDate);
+    
+    Task UpdateBudgetCategoryNameAsync(string oldName, string newName, TransactionType type);
 }
 
 public class BudgetRepository(IFreeSql freeSql) : BaseRepository<BudgetRecord>(freeSql), IBudgetRepository
@@ -33,4 +35,31 @@ public class BudgetRepository(IFreeSql freeSql) : BaseRepository<BudgetRecord>(f
 
         return await query.SumAsync(t => t.Amount);
     }
+
+    public async Task UpdateBudgetCategoryNameAsync(string oldName, string newName, TransactionType type)
+    {
+        var records = await FreeSql.Select<BudgetRecord>()
+            .Where(b => b.SelectedCategories.Contains(oldName) && 
+                        ((type == TransactionType.Expense && b.Category == BudgetCategory.Expense) ||
+                         (type == TransactionType.Income && b.Category == BudgetCategory.Income) ||
+                         (type == TransactionType.None && b.Category == BudgetCategory.Savings)))
+            .ToListAsync();
+
+        foreach (var record in records)
+        {
+            var categories = record.SelectedCategories.Split(',').ToList();
+            for (int i = 0; i < categories.Count; i++)
+            {
+                if (categories[i] == oldName)
+                {
+                    categories[i] = newName;
+                }
+            }
+            record.SelectedCategories = string.Join(',', categories);
+        }
+
+        await FreeSql.Update<BudgetRecord>()
+            .SetSource(records)
+            .ExecuteAffrowsAsync();
+    }
 }