Fix body battery and intensity minutes Garmin API endpoints

Body Battery:
- Change endpoint from /usersummary-service/stats/bodyBattery/dates/
  to /wellness-service/wellness/bodyBattery/reports/daily
- Parse new response format: array with bodyBatteryValuesArray time series
- Current value = last entry's level (index 2)
- YesterdayLow = min level from yesterday's data

Intensity Minutes:
- Change endpoint from /fitnessstats-service/activity
  to /usersummary-service/stats/im/weekly
- Add date parameter to function signature
- Parse new response format: array with moderateValue/vigorousValue

Endpoints verified against python-garminconnect source code.

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

src/app/api/cron/garmin-sync/route.test.ts

@@ -336,12 +336,15 @@ describe("POST /api/cron/garmin-sync", () => {
       );
     });
 
-    it("fetches intensity minutes", async () => {
+    it("fetches intensity minutes with today's date", async () => {
       mockUsers = [createMockUser()];
 
       await POST(createMockRequest(`Bearer ${validSecret}`));
 
-      expect(mockFetchIntensityMinutes).toHaveBeenCalledWith("mock-token-123");
+      expect(mockFetchIntensityMinutes).toHaveBeenCalledWith(
+        expect.stringMatching(/^\d{4}-\d{2}-\d{2}$/),
+        "mock-token-123",
+      );
     });
   });