feat(web): implement Run Execution UI and Run Results Page

[rezwanahmedsami]

• Add run execution dialog with browser selection, video toggle, SSE progress
• Add runs list page with search, filter, pagination, auto-refresh
• Add run details page with status, stats, video player, actions table
• Add new run page for selecting recordings to execute
• Add video player component with custom controls, progress bar, download
• Add run actions table with expandable rows for detailed results
• Fix videoEnabled field name mismatch between frontend and API
• Add CORS headers to video endpoint for cross-origin playback
• Skip global auth for video endpoint (uses query param token)
• Add storage/, videos/, screenshots/ to .gitignore

Tasks completed:

• Run Execution UI (P0)
• Run Results Page (P0)