Implements GET /api/profile and PUT /api/profile endpoints with validation
of HR zones (must be contiguous, non-overlapping, 0-100%). Also updates
profile migration to use correct HR zone defaults (0-20, 20-40, etc.)
that match validation requirements.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Add Profile table to store Garmin credentials and engine configuration
parameters. Implements GetProfile() and UpdateProfile() store methods with
comprehensive test coverage. The profile singleton row is automatically
initialized on migration and persists all configuration state.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
