Add local rider profiles and footer details

[ridecontrol]

What changed

• add a responsive footer Profile editor backed by IndexedDB
• store name, optional identity, profile image, rider weight, bike weight, and configurable drivetrain ratios locally
• apply rider-plus-bike mass and the configured drivetrain to terrain and virtual-shifting calculations while preserving the existing neutral defaults
• add Contact, Privacy, Terms, and richer production Version details in the footer
• embed recent merged pull-request metadata in production builds
• update privacy, terms, product documentation, and focused tests

Router status

TanStack Router is already present on main through the squash merge for #14. This branch builds on that routed application and does not reapply the stale local router commit.

Validation

• bun run ci
• 280 tests passing
• Biome clean with warnings as errors
• Tailwind diagnostics passing
• TypeScript passing
• production Vite build passing
• desktop and 390px mobile browser validation, including IndexedDB save/reload and console checks