feat: add session log usage tracking without proxy

Parse Claude Code JSONL session files (~/.claude/projects/) and Codex
SQLite database (~/.codex/state_5.sqlite) to track API usage without
requiring proxy interception. This enables usage statistics for users
who don't use the proxy feature.

Key changes:
- Add session_usage.rs: incremental JSONL parser with message.id dedup
- Add session_usage_codex.rs: import thread-level token data from Codex
- Add data_source column to proxy_request_logs (proxy/session_log/codex_db)
- Add session_log_sync table for tracking parse offsets
- Background sync every 60s + manual sync via DataSourceBar UI
- Schema migration v7→v8
- i18n support for zh/en/ja

src-tauri/src/database/schema.rs

@@ -189,7 +189,8 @@ impl Database {
             total_cost_usd TEXT NOT NULL DEFAULT '0', latency_ms INTEGER NOT NULL, first_token_ms INTEGER,
             duration_ms INTEGER, status_code INTEGER NOT NULL, error_message TEXT, session_id TEXT,
             provider_type TEXT, is_streaming INTEGER NOT NULL DEFAULT 0,
-            cost_multiplier TEXT NOT NULL DEFAULT '1.0', created_at INTEGER NOT NULL
+            cost_multiplier TEXT NOT NULL DEFAULT '1.0', created_at INTEGER NOT NULL,
+            data_source TEXT NOT NULL DEFAULT 'proxy'
         )", []).map_err(|e| AppError::Database(e.to_string()))?;
 
         conn.execute("CREATE INDEX IF NOT EXISTS idx_request_logs_provider ON proxy_request_logs(provider_id, app_type)", [])
@@ -271,6 +272,18 @@ impl Database {
         )
         .map_err(|e| AppError::Database(e.to_string()))?;
 
+        // 18. Session Log Sync 表 (会话日志同步状态)
+        conn.execute(
+            "CREATE TABLE IF NOT EXISTS session_log_sync (
+                file_path TEXT PRIMARY KEY,
+                last_modified INTEGER NOT NULL,
+                last_line_offset INTEGER NOT NULL DEFAULT 0,
+                last_synced_at INTEGER NOT NULL
+            )",
+            [],
+        )
+        .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",
@@ -400,6 +413,11 @@ impl Database {
                         Self::migrate_v6_to_v7(conn)?;
                         Self::set_user_version(conn, 7)?;
                     }
+                    7 => {
+                        log::info!("迁移数据库从 v7 到 v8（会话日志使用追踪）");
+                        Self::migrate_v7_to_v8(conn)?;
+                        Self::set_user_version(conn, 8)?;
+                    }
                     _ => {
                         return Err(AppError::Database(format!(
                             "未知的数据库版本 {version}，无法迁移到 {SCHEMA_VERSION}"
@@ -1060,6 +1078,34 @@ impl Database {
         Ok(())
     }
 
+    /// v7 -> v8: 会话日志使用追踪（无代理模式统计支持）
+    fn migrate_v7_to_v8(conn: &Connection) -> Result<(), AppError> {
+        // 1. 为 proxy_request_logs 添加 data_source 列，区分数据来源
+        if Self::table_exists(conn, "proxy_request_logs")? {
+            Self::add_column_if_missing(
+                conn,
+                "proxy_request_logs",
+                "data_source",
+                "TEXT NOT NULL DEFAULT 'proxy'",
+            )?;
+        }
+
+        // 2. 创建会话日志同步状态表
+        conn.execute(
+            "CREATE TABLE IF NOT EXISTS session_log_sync (
+                file_path TEXT PRIMARY KEY,
+                last_modified INTEGER NOT NULL,
+                last_line_offset INTEGER NOT NULL DEFAULT 0,
+                last_synced_at INTEGER NOT NULL
+            )",
+            [],
+        )
+        .map_err(|e| AppError::Database(format!("创建 session_log_sync 表失败: {e}")))?;
+
+        log::info!("v7 -> v8 迁移完成：已添加 data_source 列和 session_log_sync 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