feat: platform backbone and field capture, first part (checkpoint)

Platform backbone (plan 2026-10-13-plattform-rueckgrat), reviewed tasks:
- run roles api/worker/job/all with shared startup checks (Task 1)
- schema and migration for DomainEvent, deliveries, JobRun, ThrottlerHit (Task 2)
- audit, notifications and domain events written in the same transaction (Task 3)
- dispatcher with SKIP LOCKED claims, retries and stale release (Task 4)
- worker building blocks: tick, LISTEN/NOTIFY wake-up, health (Task 5)
- worker process and entry points (Task 6)
- throttler counters in Postgres (Task 19)
- separate keys per purpose with key ring (Task 20)
- public origin page without exact location (Task 22)
- shop keys split into read and write (Task 23)
- Kustomize base, components, overlay encry, CI validation (Task 26)

Field capture T3 (plan 2026-10-13-t3-erfassung-am-stand), reviewed tasks:
- brood frames, read endpoints, apiary overview and offline pack
- network basics, offline queue v3, navigation sheets, form building blocks
- new inspection with last-time hints and weather, varroa per day,
  treatment prefill, apiary page with round
- inspection photo (Task 10) is implemented, review pending

Not rolled out. Remaining tasks follow in later commits.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

ApiCore-Backend/src/webhooks/webhook-secret.ts

@@ -1,19 +1,36 @@
 import {
-  decryptMfaSecret,
-  encryptMfaSecret,
-} from '../auth/mfa/mfa-crypto.util';
+  KEY_ID_PATTERN,
+  isSealedWithCurrentKey,
+  loadKeyRing,
+  openLegacyCiphertext,
+  openWithRing,
+  sealWithRing,
+  warnLegacyRead,
+} from '../common/crypto/key-ring';
 
 // Webhook signing secrets must stay reversible (the server signs with them),
-// so they are stored AES-256-GCM-encrypted like TOTP secrets. Rows written
-// before this carry the plain secret and no prefix - still readable.
-const PREFIX = 'enc:v1:';
+// so they are sealed with the webhook key ring (WEBHOOK_ENCRYPTION_KEY, see
+// common/crypto/key-ring.ts). Two older forms stay readable until the rekey
+// job reseals them: "enc:v1:" + a ciphertext under sha256(JWT_ACCESS_SECRET),
+// and, from before encryption, the plain secret without any prefix.
+const LEGACY_PREFIX = 'enc:v1:';
 
 export function sealWebhookSecret(secret: string): string {
-  return `${PREFIX}${encryptMfaSecret(secret)}`;
+  return sealWithRing(loadKeyRing('webhook'), secret);
 }
 
 export function openWebhookSecret(stored: string): string {
-  return stored.startsWith(PREFIX)
-    ? decryptMfaSecret(stored.slice(PREFIX.length))
-    : stored;
+  if (KEY_ID_PATTERN.test(stored)) {
+    return openWithRing(loadKeyRing('webhook'), stored).plaintext;
+  }
+  if (stored.startsWith(LEGACY_PREFIX)) {
+    return openLegacyCiphertext('webhook', stored.slice(LEGACY_PREFIX.length));
+  }
+  warnLegacyRead('webhook');
+  return stored;
+}
+
+/** True for secrets the rekey job should reseal with the current key. */
+export function webhookSecretNeedsRekey(stored: string): boolean {
+  return !isSealedWithCurrentKey(loadKeyRing('webhook'), stored);
 }