feat(frontend): add LogsPage with stats, filters and pagination

- New LogsPage.tsx under features/logs/ (was referenced by router but missing)
- Uses existing useLogs / useLogStats / useLogLevels hooks
- Stats cards (24h total, errors, failed logins, page count)
- Search + level filter + pagination wired to /logs/api/logs
- i18n strings, lucide icons, shadcn UI primitives

Fix frontend/.gitignore: '/logs' was matching 'features/logs/' (rolldown-vite
import resolution would have kept failing on CI otherwise). Scope the rule
to the project root.

frontend/.gitignore

@@ -1,5 +1,5 @@
-# Logs
-logs
+# Logs (root-level runtime logs only; do NOT match src/features/logs/)
+/logs
 *.log
 npm-debug.log*
 yarn-debug.log*