feat(fe): optimize error handling, state consistency, and WS feedback

- Add global SWR config with exponential backoff retry (swr-config.ts)
- Add ErrorBoundary component for React crash recovery (error-boundary.tsx)
- Standardize ErrorState onRetry on all 6 dashboard views (dashboard, media,
  messages, moderation, recordings, voice)
- Fix useAction: expose resetError + onError callback
- Refactor useSpeakers to SWR-backed state (was local useState) for
  consistent cache/revalidate semantics with other hooks
- Remove polling in useReview (15s refreshInterval); replace with
  useReviewWsSync subscribing to WS moderation_action events
- Extract hashUserId to lib/hash.ts (de-dup with ambient-canvas)
- WS context: add reconnect/error toast feedback via onStatusChange
- WS connection: expose reconnectAttemptCount getter

All typecheck + lint clean, Next 16 build passes.

services/frontend/src/lib/hash.ts

@@ -0,0 +1,12 @@
+/**
+ * FNV-1a 32-bit hash — same hash the gateway uses to tag PCM frames.
+ * Shared between use-voice hooks and ambient-canvas.
+ */
+export function hashUserId(userId: string): number {
+  let hash = 0x811c9dc5;
+  for (let i = 0; i < userId.length; i++) {
+    hash ^= userId.charCodeAt(i);
+    hash = Math.imul(hash, 0x01000193);
+  }
+  return hash >>> 0;
+}