Move BikeGPX processing off-device and add FIT support

[ridecontrol]

What changed

• move the frontend from GitHub Pages to a Cloudflare static-assets Worker at ridecontrol.xyz
• browse the backend-managed BikeGPX catalog and process routes only when a rider selects one
• show route distances consistently in the dashboard's selected units
• store saved-session workout snapshots efficiently in IndexedDB
• import and export Strava-compatible FIT activities while retaining TCX round-trip support
• update repository links for the RideControlOrg organization

Why

This keeps BikeGPX origin access and route processing off the rider's device, avoids unnecessary route work, makes activity uploads more compatible with Strava, and consolidates frontend hosting on Cloudflare.

Impact

• route selection can briefly show a queued state while the backend prepares an uncached route
• FIT becomes the default batch-export format; TCX remains available for Ride Control-specific metadata
• the application is served from the apex ridecontrol.xyz domain

Validation

• bun run ci
• 235 unit tests and 1,411 assertions
• Ultracite/Biome checks
• Tailwind CSS diagnostics
• TypeScript typecheck
• Vite production build