Add profile-driven config infrastructure:
- config/profiles/{home,regional_pi,minimal_pi}.yaml templates
- lib/deployment_config.py loader (reads RECON_PROFILE env var)
- GET /api/config returns active profile as JSON (5min cache)
Frontend reads this on startup to determine tile source, defaults,
and feature flags. No existing behavior changed.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
