File uploads, deliverables, and a proper admin panel

Rebuilt the admin dashboard from the ground up. It now tracks every active project, open action item, pending deliverable, and upcoming booking in one place. Added Cloudflare R2 for file storage so I can upload session recordings, stems, and documents directly from the admin panel. Clients see their deliverables with status tracking and can download files through signed URLs. Drag-and-drop uploads on desktop, tap-to-upload on mobile. The whole admin experience is mobile-first now because half the time I'm managing projects from my phone.