Fix VO2 max extraction from training_status.mostRecentVO2Max.generic

Correct path confirmed from live API response. Store against the actual
measurement date (calendarDate from the VO2 max record) rather than
today, so the carry-forward logic shows the right value from the correct
day. Also store fitnessAge from the fitnessage endpoint alongside it.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/services/garmin_connect_sync.py

@@ -325,40 +325,23 @@ def sync_wellness(garmin, user_id: int, since: Optional[datetime], db,
             logger.warning("Failed to upsert health_metrics for %s: %s", day_str, exc)
             db.rollback()
 
-    # Fetch current VO2 max once (slow-changing — only update today's row)
+    # Fetch VO2 max from training status (slow-changing — store against measurement date)
     today_str = date.today().isoformat()
     ts_data = _safe(garmin.get_training_status, today_str)
-    logger.info("training_status raw response: %s", ts_data)
-    sb_data  = _safe(garmin.get_stats_and_body, today_str)
-    logger.info("stats_and_body raw response: %s", sb_data)
     fa_data = _safe(garmin.get_fitnessage_data, today_str)
 
     vo2 = None
-    # Try training status first
-    if ts_data and not vo2:
-        for key in ("vo2MaxPreciseValue", "vo2Max", "latestVO2Max"):
-            v = ts_data.get(key)
-            if v and isinstance(v, (int, float)) and float(v) > 0:
-                vo2 = float(v)
-                break
-        if not vo2 and isinstance(ts_data.get("mostRecentVO2Max"), dict):
-            v = ts_data["mostRecentVO2Max"].get("generic") or ts_data["mostRecentVO2Max"].get("value")
+    vo2_date = today_str
+    generic = (ts_data or {}).get("mostRecentVO2Max", {}).get("generic") or {}
+    v = generic.get("vo2MaxPreciseValue") or generic.get("vo2MaxValue")
     if v and float(v) > 0:
         vo2 = float(v)
-    # Try stats_and_body
-    if sb_data and not vo2:
-        for key in ("vo2MaxPreciseValue", "vo2Max"):
-            v = sb_data.get(key)
-            if v and isinstance(v, (int, float)) and float(v) > 0:
-                vo2 = float(v)
-                break
+        vo2_date = generic.get("calendarDate") or today_str
 
     fa_age = None
     if fa_data:
         fa_age = fa_data.get("fitnessAge") or fa_data.get("achievableFitnessAge")
 
-    logger.info("parsed vo2=%s fitness_age=%s", vo2, fa_age)
-
     if vo2:
         try:
             fa_row = {"vo2max": vo2}
@@ -370,8 +353,9 @@ def sync_wellness(garmin, user_id: int, since: Optional[datetime], db,
                 VALUES (:user_id, :day, {", ".join(f":{c}" for c in fa_cols)})
                 ON CONFLICT (user_id, date) DO UPDATE SET
                 {", ".join(f"{c} = EXCLUDED.{c}" for c in fa_cols)}
-            """), {"user_id": user_id, "day": today_str, **fa_row})
+            """), {"user_id": user_id, "day": vo2_date, **fa_row})
             db.commit()
+            logger.info("Stored VO2 max %.1f for %s", vo2, vo2_date)
         except Exception as exc:
             logger.warning("Failed to upsert VO2 max: %s", exc)
             db.rollback()