chore: migrate remaining ECharts components to Chart.js

- Migrated 4 components from ECharts to Chart.js:
  * MonthlyExpenseCard.vue (折线图)
  * DailyTrendChart.vue (双系列折线图)
  * ExpenseCategoryCard.vue (环形图)
  * BudgetChartAnalysis.vue (仪表盘 + 多种图表)

- Removed all ECharts imports and environment variable switches
- Unified all charts to use BaseChart.vue component
- Build verified: pnpm build success ✓
- No echarts imports remaining ✓

Refs: openspec/changes/migrate-remaining-echarts-to-chartjs

Database/Migrations/001_AddIconKeywordsToTransactionCategory.sql

@@ -0,0 +1,12 @@
+-- 数据库迁移：为TransactionCategory表添加IconKeywords字段
+-- 修改Icon字段长度限制
+
+-- 步骤1：修改Icon字段长度限制（如果字段已存在且长度为-1）
+-- SQLite不支持直接修改字段长度，需要重建表或使用其他方法
+-- 由于这是SQLite，我们假设Icon字段已存在，只需添加IconKeywords字段
+
+-- 步骤2：添加IconKeywords字段
+ALTER TABLE TransactionCategory ADD COLUMN IconKeywords TEXT;
+
+-- 验证
+-- PRAGMA table_info(TransactionCategory);