Refactor global schedules with mobile-responsive UI and backend optimizations

[chriswritescode-dev]

Summary

• Refactor GlobalSchedules page with mobile-responsive filter UI using DropdownMenu
• Remove selectedJob state, simplify job action handlers
• Add mobile navigation button in Repos page for schedules
• Update backend to derive repo name from path instead of database column
• Improve responsive layout with conditional rendering for mobile/desktop

Why

Improves mobile UX by providing accessible filter controls and navigation while simplifying the backend data model by deriving repo names from paths rather than storing redundant data.

What Is Included

• GlobalSchedules.tsx: Mobile-responsive filters, simplified state management
• Repos.tsx: Mobile schedules navigation button
• backend/src/db/schedules.ts: repoNameFromPath utility, query optimization

Type Of Change

• New feature
• Refactoring
• UI/UX improvement

Checklist

• Code follows project style
• Types updated
• pnpm lint passes