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/i18n/locales/en.json

@@ -1018,6 +1018,21 @@
     "unknownProvider": "Unknown Provider",
     "stream": "Stream",
     "nonStream": "Non-stream",
+    "source": "Source",
+    "dataSources": "Data Sources",
+    "dataSource": {
+      "proxy": "Proxy",
+      "session_log": "Session Log",
+      "codex_db": "Codex DB"
+    },
+    "sessionSync": {
+      "trigger": "Sync session logs",
+      "import": "Import Sessions",
+      "resync": "Sync",
+      "imported": "Imported {{count}} records from session logs",
+      "upToDate": "Session logs are up to date",
+      "failed": "Session sync failed"
+    },
     "totalRecords": "{{total}} records total",
     "modelPricing": "Model Pricing",
     "loadPricingError": "Failed to load pricing data",

src/i18n/locales/ja.json

@@ -1018,6 +1018,21 @@
     "unknownProvider": "不明なプロバイダー",
     "stream": "ストリーム",
     "nonStream": "非ストリーム",
+    "source": "ソース",
+    "dataSources": "データソース",
+    "dataSource": {
+      "proxy": "プロキシ",
+      "session_log": "セッションログ",
+      "codex_db": "Codex DB"
+    },
+    "sessionSync": {
+      "trigger": "セッションログを同期",
+      "import": "セッションをインポート",
+      "resync": "同期",
+      "imported": "セッションログから {{count}} 件のレコードをインポートしました",
+      "upToDate": "セッションログは最新です",
+      "failed": "セッション同期に失敗しました"
+    },
     "totalRecords": "全 {{total}} 件",
     "modelPricing": "モデル料金",
     "loadPricingError": "料金データの読み込みに失敗しました",

src/i18n/locales/zh.json

@@ -1018,6 +1018,21 @@
     "unknownProvider": "未知供应商",
     "stream": "流",
     "nonStream": "非流",
+    "source": "来源",
+    "dataSources": "数据来源",
+    "dataSource": {
+      "proxy": "代理",
+      "session_log": "会话日志",
+      "codex_db": "Codex 数据库"
+    },
+    "sessionSync": {
+      "trigger": "同步会话日志",
+      "import": "导入会话",
+      "resync": "同步",
+      "imported": "从会话日志导入了 {{count}} 条记录",
+      "upToDate": "会话日志已是最新",
+      "failed": "会话同步失败"
+    },
     "totalRecords": "共 {{total}} 条记录",
     "modelPricing": "模型定价",
     "loadPricingError": "加载定价数据失败",