debug: add logging to Apple Health import to diagnose skipped rows

Logs:
- CSV column names from first row
- Rows skipped due to missing date
- Rows skipped due to no vitals data
- Shows which fields were found/missing

Helps diagnose CSV format mismatches.

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

backend/routers/vitals_baseline.py

@@ -311,10 +311,18 @@ async def import_apple_health_baseline(
     with get_db() as conn:
         cur = get_cursor(conn)
 
+        # Log available columns for debugging
+        first_row = True
+
         for row in reader:
             try:
+                if first_row:
+                    logger.info(f"CSV Columns: {list(row.keys())}")
+                    first_row = False
+
                 date = row.get('Start')[:10] if row.get('Start') else None
                 if not date:
+                    logger.warning(f"Skipped row (no date): Start='{row.get('Start')}'")
                     skipped += 1
                     continue
 
@@ -327,6 +335,7 @@ async def import_apple_health_baseline(
 
                 # Skip if no baseline vitals
                 if not any([rhr, hrv, vo2, spo2, resp_rate]):
+                    logger.warning(f"Skipped row {date} (no vitals): RHR={rhr}, HRV={hrv}, VO2={vo2}, SpO2={spo2}, RespRate={resp_rate}")
                     skipped += 1
                     continue