Add debug logging for body battery API response

Need to inspect the raw response structure to debug why current
and yesterdayLow values are missing despite hasCurrentData=true.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/lib/garmin.ts

@@ -142,6 +142,12 @@ export async function fetchBodyBattery(
       bodyBatteryValuesArray?: Array<[number, string, number, number]>;
     }>;
 
+    // Debug: log the raw response structure
+    logger.info(
+      { rawData: JSON.stringify(data).slice(0, 2000), date, yesterday },
+      "Body battery raw API response",
+    );
+
     // Find today's and yesterday's data from the response array
     const todayData = data?.find((d) => d.date === date);
     const yesterdayData = data?.find((d) => d.date === yesterday);