Fitbit Air: Health Connect sync + vitals dashboard

- react-native-health-connect (config plugin, minSdk 26, 11 read perms)
- sync-on-open + manual sync: incremental via server watermark, chunked
  POST to /api/health/v1/fitbit/sync (HR, resting HR, HRV, SpO2, resp
  rate, steps/distance/kcal/floors dailies, staged sleep sessions)
- Fitbit screen: steps/RHR/HRV/SpO2 tiles + daily charts + sleep list +
  per-stream record counts (answers the which-types-does-Google-Health-
  share question empirically)
- Sleep tab now merges Fitbit Air nights (wins over older sources)
- Today screen Fitbit card

Server side (deployed separately on VPS): hc_samples/hc_daily/hc_sleep
tables + sync/latest/summary endpoints in health-api; Caddy routes POST
/api/health/v1/fitbit/* behind the same basic_auth.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

package.json

@@ -22,6 +22,7 @@
     "react-dom": "19.2.3",
     "react-native": "0.86.2",
     "react-native-gesture-handler": "~2.32.0",
+    "react-native-health-connect": "^4.1.3",
     "react-native-reanimated": "4.5.1",
     "react-native-safe-area-context": "~5.7.0",
     "react-native-screens": "~4.26.0",
@@ -31,6 +32,7 @@
   },
   "devDependencies": {
     "@types/react": "~19.2.2",
+    "expo-build-properties": "^57.0.9",
     "typescript": "~6.0.3"
   },
   "scripts": {