Real-time WebSocket Activity Feed

[sepulchralvoid666]

Bounty #860 — Real-time WebSocket Activity Feed

What

• WebSocket connection with automatic reconnect (exponential backoff, max 30s)
• Polling fallback after 3 failed WS attempts (15s interval)
• Event dedup and cap (200 events max)
• Notification preferences persisted to localStorage
• Filter bar by event type (platform + on-chain)
• Activity event cards with icon, timestamp, actor, bounty link, amount, source badge
• Shimmer skeleton loading state
• Route at /activity with nav link in Navbar

Files

• types/activity.ts — Full type system (ActivityEvent, FeedEventType, OnChainEventType, NotificationPreferences, ConnectionStatus, label/icon helpers)
• hooks/useActivityFeed.ts — Core hook (WS, reconnect, polling, dedup, filter, prefs)
• components/activity/ActivityFeed.tsx — Main feed with header, status, prefs panel, filters
• components/activity/ActivityEventCard.tsx — Individual event card
• components/activity/ActivityFilterBar.tsx — Event type filter pills
• components/activity/NotificationPreferences.tsx — Per-type notification toggles
• components/activity/ActivityFeedSkeleton.tsx — Shimmer loading state
• pages/ActivityPage.tsx — Page wrapper
• Route + nav link additions to App.tsx and Navbar.tsx

Acceptance Criteria

• Real-time updates via WebSocket
• Graceful reconnection with exponential backoff
• Polling fallback when WS unavailable
• Notification preferences (localStorage persisted)
• Event filtering by type
• Connection status indicator
• Manual reconnect button
• Skeleton loading states
• Responsive layout

Closes #860

Solana wallet for payout: 9PmjWFwM2mdnjBNjJyfNMTWGCnGAKFpywsLF9xcRF8PK

[nagiexplorer88]

This PR currently has a build-blocking import in the new skeleton file.

frontend/src/components/activity/ActivityFeedSkeleton.tsx imports:

import { ShimmerBlock } from "./Skeleton";

There is no frontend/src/components/activity/Skeleton.tsx in this PR. The skeleton helper added in the repo is under frontend/src/components/ui/Skeleton.tsx, and in that file ShimmerBlock is not exported as a named export. So TypeScript/Vite will fail resolving this import before the /activity route can build.

The smallest fix is either to make ActivityFeedSkeleton use the exported skeleton components from ../ui/Skeleton, or export ShimmerBlock from the shared UI skeleton module and import it via the correct relative path.