feat(frontend): Implement client-side SSE handling (#35)

Implements real-time event streaming on the frontend with:

- Event types and type guards matching backend EventType enum
- Zustand-based event store with per-project buffering
- useProjectEvents hook with auto-reconnection and exponential backoff
- ConnectionStatus component showing connection state
- EventList component with expandable payloads and filtering

All 105 tests passing. Follows design system guidelines.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/lib/hooks/index.ts

@@ -0,0 +1,7 @@
+/**
+ * Custom React Hooks
+ *
+ * @module lib/hooks
+ */
+
+export { useProjectEvents, type UseProjectEventsOptions, type UseProjectEventsResult } from './useProjectEvents';