feat: replace Codex estimated usage with precise JSONL session log parsing

Replace the 70/30 input/output token estimation from state_5.sqlite
with precise parsing of Codex CLI JSONL session logs (~/.codex/sessions/).

- Parse event_msg (token_count), turn_context, and session_meta events
- Compute exact input/output/cached token deltas from cumulative totals
- Reuse session_log_sync table for incremental file scanning
- Pre-filter lines with string contains() before JSON deserialization
- Add codex_session data source to DataSourceBar with i18n (zh/en/ja)

src/components/usage/DataSourceBar.tsx

@@ -15,6 +15,7 @@ const DATA_SOURCE_ICONS: Record<string, React.ReactNode> = {
   proxy: <Database className="h-3.5 w-3.5" />,
   session_log: <FileText className="h-3.5 w-3.5" />,
   codex_db: <Database className="h-3.5 w-3.5" />,
+  codex_session: <FileText className="h-3.5 w-3.5" />,
 };
 
 export function DataSourceBar({ refreshIntervalMs }: DataSourceBarProps) {