chore(glp1): test-environment tolerance + i18n parity + OpenAPI regen

Final-pass hygiene for the W4d GLP-1 integration:

- `buildGlp1SnapshotBlock()` and `detectGlp1Plateau()` short-circuit
  to `null` when the test environment mocks prisma partially (only
  `measurement` / `moodEntry` mocked, `medication` undefined). Matches
  the production behaviour for accounts without an active GLP-1 row.
- DE locale parity: adds the matching German string for
  `insights.subPage.therapyTimelineDescription` that landed without
  its de.json counterpart.
- Drops unused `locale` destructure on the GLP-1 medication card and
  the dead `DailyValueRow` interface in the snapshot helper.
- Regenerated `docs/api/openapi.yaml` so the new GLP-1 endpoints
  (/api/medications/[id]/glp1, /api/insights/glp1-timeline) appear
  in the spec.

src/components/medications/glp1-medication-card.tsx

@@ -156,7 +156,7 @@ export function Glp1MedicationCard({
   onLogSideEffect,
 }: Glp1MedicationCardProps) {
   const queryClient = useQueryClient();
-  const { t, locale } = useTranslations();
+  const { t } = useTranslations();
   const fmt = useFormatters();
   const [intakeLoading, setIntakeLoading] = useState<string | null>(null);
   const [showHistory, setShowHistory] = useState(false);