Add specific fetchers for HRV, Body Battery, and Intensity Minutes
to enable real biometric data collection from Garmin Connect API.
Functions added:
- fetchHrvStatus(): Returns "Balanced", "Unbalanced", or "Unknown"
- fetchBodyBattery(): Returns current BB and yesterday's low value
- fetchIntensityMinutes(): Returns 7-day rolling sum of activity
All functions gracefully handle API failures with safe defaults.
Test count expanded from 14 to 33 covering all scenarios.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>