chore(images): pin service image updates

Replace floating service images with reviewable tags or digests.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

gitea/k8s/postgres.yaml

@@ -29,7 +29,7 @@ spec:
     spec:
       containers:
         - name: gitea-postgres
-          image: postgres:14
+          image: postgres:14.24-alpine
           env:
             - name: POSTGRES_USER
               valueFrom:
@@ -45,7 +45,7 @@ spec:
               valueFrom:
                 secretKeyRef:
                   name: gitea-secrets
-                  key: GITEA__database__USER
+                  key: GITEA__database__NAME
           ports:
             - containerPort: 5432
               name: postgres