feat: implement activity feed with filterable timeline for project history (#3184)

[knoxiboy]

Summary

This PR implements a project-wide activity history feed and timeline showing updates across tasks and workflow columns. The feed includes a beautiful filterable timeline (filter by action type and date range) and supports pagination/loading more logs.

Closes #3184

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Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that changes existing behavior)
• 📝 Documentation update
• ♻️ Refactor / code cleanup (no functional change)
• ⚡ Performance improvement
• 🔒 Security fix
• 🧪 Tests only

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What Changed

• Database / Schema:
  • supabase/migrations/20260715000001_add_activity_log.sql: Created activity_log table referencing projects and users with indexing and RLS security policies.
• Backend / API:
  • src/app/api/kanban/[projectId]/activity/route.ts: API route returning filterable and paginated activity logs.
  • src/app/api/kanban/[projectId]/stages/route.ts: Updated to record stage_created, stage_deleted, and stages_reordered actions.
  • src/app/api/kanban/[projectId]/tasks/route.ts: Updated to record task_created, task_deleted, task_updated, and task_moved actions.
• Frontend / UI Components:
  • src/components/kanban/ActivityFeed.tsx: Renders the vertical timeline with action icon badges, local time formatting, action/date filters, and lazy-loading pagination.
  • src/components/kanban/KanbanBoard.tsx: Integrated the feed side-panel with a responsive header toggle button.

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How to Test

1. Navigate to a Kanban board page (e.g. /dashboard/kanban/[projectId]).
2. Click the "Show History" button in the board header.
3. Verify that adding a task, reordering columns, deleting a task, or moving cards between columns live-updates and populates the history timeline.
4. Test filtering by action types (e.g. "Task Moved") and selecting date ranges to ensure logs filter accurately.
5. Click "Load More Activities" to verify offset pagination works.

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Checklist

• Linked the related issue above
• Self-reviewed my own diff
• No unnecessary console.log, debug code, or commented-out blocks
• npm run lint passes locally (Eslint setup failed locally on native dependency issue)
• No TypeScript errors (npm run type-check)
• Added or updated tests where applicable
• Updated documentation / comments if behavior changed

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Accessibility (UI changes only)

• Keyboard navigation works correctly
• Color contrast meets WCAG AA standard
• ARIA labels / roles added where needed
• Tested on mobile / responsive layout

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Additional Context

• Action badges are colored-coded by impact (green for creations, red for deletions, indigo for movements/reorders) to allow quick scanning of board history.

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[github-actions]

GSSoC Label Checklist 🏷️

@Priyanshu-byte-coder — please apply the appropriate labels before merging:

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