refactor(apps): move forte-drop postgres from infra to apps

Per reviewer (danijel): forte-drop's DB deployment belongs in apps/,
not infra/. Straight relocation — same structure (Application +
resources/ subdir), source.path updated to apps/base/forte-drop-postgresql/resources,
wired into apps/overlays/upc-dev. Backup CronJob + RESTORE.md + sealed
pg creds move with it.

Consolidates the whole forte-drop deployment (postgres + web + mcp)
under apps/. The infra PR (#17) is now superseded by this.

apps/base/forte-drop-postgresql/forte-drop-postgresql.yaml

@@ -0,0 +1,40 @@
+apiVersion: argoproj.io/v1alpha1
+kind: Application
+metadata:
+  name: forte-drop-postgresql
+  namespace: argocd
+  annotations:
+    argocd.argoproj.io/sync-wave: "0"
+  labels:
+    app.kubernetes.io/name: forte-drop-postgresql
+    app.kubernetes.io/part-of: apps
+    app.kubernetes.io/managed-by: argocd
+  finalizers:
+  - resources-finalizer.argocd.argoproj.io
+spec:
+  project: default
+
+  source:
+    repoURL: ssh://git@git.forteapps.net:2222/Forte/launchpad.git
+    targetRevision: HEAD
+    path: apps/base/forte-drop-postgresql/resources
+
+  destination:
+    server: https://kubernetes.default.svc
+    namespace: forte-drop
+
+  syncPolicy:
+    automated:
+      prune: true
+      selfHeal: true
+      allowEmpty: false
+    syncOptions:
+    - CreateNamespace=true
+    - Validate=true
+    - ServerSideApply=true
+
+  ignoreDifferences:
+  - group: apps
+    kind: StatefulSet
+    jsonPointers:
+    - /spec/volumeClaimTemplates