feat: add usage daily rollups, incremental auto-vacuum, and sync-aware backup

- Add usage_daily_rollups table (schema v6) to aggregate proxy request
  logs into daily summaries, reducing query overhead for statistics
- Add rollup_and_prune DAO that aggregates old detail logs (>N days)
  into rollup rows and deletes the originals
- Update all usage stats queries to UNION detail logs with rollup data
- Introduce incremental auto-vacuum for SQLite, with startup and
  periodic cleanup of old stream_check_logs and request log rollups
- Split backup export/import into full vs sync variants: WebDAV sync
  now skips local-only table data (proxy_request_logs,
  stream_check_logs, provider_health, proxy_live_backup,
  usage_daily_rollups) while preserving them on import
- Add enable_logging guard to skip request log writes when disabled
- Apply cargo fmt formatting fixes across multiple modules

src-tauri/src/database/schema.rs

@@ -241,6 +241,27 @@ impl Database {
         )
         .map_err(|e| AppError::Database(e.to_string()))?;
 
+        // 17. Usage Daily Rollups 表 (日聚合统计)
+        conn.execute(
+            "CREATE TABLE IF NOT EXISTS usage_daily_rollups (
+                date TEXT NOT NULL,
+                app_type TEXT NOT NULL,
+                provider_id TEXT NOT NULL,
+                model TEXT NOT NULL,
+                request_count INTEGER NOT NULL DEFAULT 0,
+                success_count INTEGER NOT NULL DEFAULT 0,
+                input_tokens INTEGER NOT NULL DEFAULT 0,
+                output_tokens INTEGER NOT NULL DEFAULT 0,
+                cache_read_tokens INTEGER NOT NULL DEFAULT 0,
+                cache_creation_tokens INTEGER NOT NULL DEFAULT 0,
+                total_cost_usd TEXT NOT NULL DEFAULT '0',
+                avg_latency_ms INTEGER NOT NULL DEFAULT 0,
+                PRIMARY KEY (date, app_type, provider_id, model)
+            )",
+            [],
+        )
+        .map_err(|e| AppError::Database(e.to_string()))?;
+
         // 尝试添加 live_takeover_active 列到 proxy_config 表
         let _ = conn.execute(
             "ALTER TABLE proxy_config ADD COLUMN live_takeover_active INTEGER NOT NULL DEFAULT 0",
@@ -360,6 +381,11 @@ impl Database {
                         Self::migrate_v4_to_v5(conn)?;
                         Self::set_user_version(conn, 5)?;
                     }
+                    5 => {
+                        log::info!("迁移数据库从 v5 到 v6（使用量聚合表）");
+                        Self::migrate_v5_to_v6(conn)?;
+                        Self::set_user_version(conn, 6)?;
+                    }
                     _ => {
                         return Err(AppError::Database(format!(
                             "未知的数据库版本 {version}，无法迁移到 {SCHEMA_VERSION}"
@@ -914,6 +940,32 @@ impl Database {
         Ok(())
     }
 
+    /// v5 -> v6 迁移：添加使用量日聚合表
+    fn migrate_v5_to_v6(conn: &Connection) -> Result<(), AppError> {
+        conn.execute(
+            "CREATE TABLE IF NOT EXISTS usage_daily_rollups (
+                date TEXT NOT NULL,
+                app_type TEXT NOT NULL,
+                provider_id TEXT NOT NULL,
+                model TEXT NOT NULL,
+                request_count INTEGER NOT NULL DEFAULT 0,
+                success_count INTEGER NOT NULL DEFAULT 0,
+                input_tokens INTEGER NOT NULL DEFAULT 0,
+                output_tokens INTEGER NOT NULL DEFAULT 0,
+                cache_read_tokens INTEGER NOT NULL DEFAULT 0,
+                cache_creation_tokens INTEGER NOT NULL DEFAULT 0,
+                total_cost_usd TEXT NOT NULL DEFAULT '0',
+                avg_latency_ms INTEGER NOT NULL DEFAULT 0,
+                PRIMARY KEY (date, app_type, provider_id, model)
+            )",
+            [],
+        )
+        .map_err(|e| AppError::Database(format!("创建 usage_daily_rollups 表失败: {e}")))?;
+
+        log::info!("v5 -> v6 迁移完成：已添加使用量日聚合表");
+        Ok(())
+    }
+
     /// 插入默认模型定价数据
     /// 格式: (model_id, display_name, input, output, cache_read, cache_creation)
     /// 注意: model_id 使用短横线格式（如 claude-haiku-4-5），与 API 返回的模型名称标准化后一致