refactor(temporal): adopt unified CNPG pattern - use 'app' user

CHANGES:
  - temporal-values.yaml: user 'app', existingSecret 'ddb-cluster-app'
  - bootstrap.sh: Copy ddb-cluster-app to temporal namespace
  - Removed db-secret-sync directory (obsolete PostSync Job)
  - 60-applications.yaml: Removed db-secret-sync source from temporal Application

PATTERN (same as Forgejo/Authentik):
  1. Database CR: owner app
  2. bootstrap.sh: Copy ddb-cluster-app to temporal namespace
  3. App values: Reference ddb-cluster-app secret
  4. No PostSync Jobs needed

FIXES:
  - Temporal schema CrashLoopBackOff (wrong credentials)
  - Dropped/recreated databases with app owner (clean state)

Following CLAUDE.md CNPG pattern documentation.

bootstrap.sh

@@ -88,6 +88,12 @@ kubectl get secret ddb-cluster-app -n ddb -o yaml \
   | sed 's/namespace: ddb/namespace: iam/' \
   | kubectl apply -f -
 
+
+# Copy DB secret to temporal namespace (for temporal)
+log "Copying ddb-cluster-app secret to temporal namespace..."
+kubectl get secret ddb-cluster-app -n ddb -o yaml \
+  | sed 's/namespace: ddb/namespace: temporal/' \
+  | kubectl apply -f -
 # 7. Wait for Forgejo
 log "Waiting for Forgejo to be ready..."
 kubectl wait --for=condition=available --timeout=600s \