feat(mental-health): opt-in PHQ-9 / GAD-7 screeners with item-9 crisis signposting

Add the validated mental-health self-assessment surface, beside mood tracking
(never replacing it) and off by default:

- MentalHealthAssessment stores per-item answers in a single AES-256-GCM Bytes
  blob (registered for key rotation); only the server-authoritative total,
  severity band, and item-9 flag are denormalised. The total projects to a
  PHQ9_SCORE / GAD7_SCORE measurement row so the trend rides existing infra
  without ever exposing item content.
- Item-9 safety: any non-zero PHQ-9 self-harm answer surfaces a calm,
  locale-aware crisis-resource set (DE: TelefonSeelsorge 0800 111 0 111 / 112;
  international fallback) and stamps crisisShownAt. No clinical interpretation,
  no AI ingestion of item content, no third-party alerting.
- API + OpenAPI: POST/GET /api/mental-health/assessments; the response excludes
  raw item answers by construction. Required Pfizer/PHQ attribution lives in the
  instrument module, rendered verbatim.

The screener scores are kept off the Coach snapshot and MCP surfaces, and out of
exports by default — item content never reaches the AI pipeline.

scripts/rotate-encryption-key.ts

@@ -448,6 +448,17 @@ async function main() {
     ),
   );
 
+  // ───── v1.25 mental-health screener item answers (Bytes column) ─────
+  // The PHQ-9 / GAD-7 encrypted per-item blob. Always present (NOT NULL), so
+  // every row rotates.
+  results.push(
+    await rotateBytesColumn(
+      "MentalHealthAssessment",
+      "responsesEncrypted",
+      prisma.mentalHealthAssessment,
+    ),
+  );
+
   console.log("\n=== Rotation summary ===");
   let totalRotated = 0;
   let totalErrors = 0;