feat: add duplicate schedule lock, cross-tab sync, tab validation and debounce

[DebasmitaBose0]

Closes #419

Summary

Prevents duplicate scheduled refresh runs, adds cross-tab state sync, and validates tab query parameters with debounced switching.

Changes

• supabase/migrations/20260714000000_add_scheduler_locks.sql — new scheduler_locks table for exclusive cron locks
• supabase/functions/scheduled-refresh/index.ts — acquire/release lock via upsert; skips if concurrent run active; release on error
• src/hooks/useBroadcastChannel.ts — new: BroadcastChannel API hook for cross-tab communication
• src/hooks/useVisibility.ts — new: visibilitychange listener hook
• src/components/profile/ProfileView.tsx — debounced tab switching (150ms), cross-tab refresh sync via BroadcastChannel, pause relative-time updates on tab hide
• src/app/explore/page.tsx — whitelist validation for sortBy and type query params

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Configuration used: Organization UI

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Run ID: 4dd5aab5-3671-43e8-a599-801b2d38eb80

📥 Commits

Reviewing files that changed from the base of the PR and between 294511e and 4385b05.

📒 Files selected for processing (6)

• src/app/explore/page.tsx
• src/components/profile/ProfileView.tsx
• src/hooks/useBroadcastChannel.ts
• src/hooks/useVisibility.ts
• supabase/functions/scheduled-refresh/index.ts
• supabase/migrations/20260714000000_add_scheduler_locks.sql

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🧪 Generate unit tests (beta)

• Create PR with unit tests

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[github-actions]

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[github-actions]

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