arrstack: gate apps on DB via initContainer instead of sync-waves

Per review: drop the ArgoCD sync-wave annotations (their health-gating is
what deadlocked the first deploy) and instead add a wait-for-db init
container to each app that blocks until its own Postgres database+role is
reachable (libpq PG* env, password never in argv). ArgoCD applies
everything at once; the app container only starts once its DB is ready.

apps/base/arrstack/postgres/vaultstaticsecret.yaml

@@ -13,8 +13,6 @@ kind: VaultStaticSecret
 metadata:
   name: sonarr-db
   namespace: arrstack
-  annotations:
-    argocd.argoproj.io/sync-wave: "-3"
 spec:
   destination:
     create: true
@@ -32,8 +30,6 @@ kind: VaultStaticSecret
 metadata:
   name: radarr-db
   namespace: arrstack
-  annotations:
-    argocd.argoproj.io/sync-wave: "-3"
 spec:
   destination:
     create: true
@@ -51,8 +47,6 @@ kind: VaultStaticSecret
 metadata:
   name: prowlarr-db
   namespace: arrstack
-  annotations:
-    argocd.argoproj.io/sync-wave: "-3"
 spec:
   destination:
     create: true