feat(apps): forte-drop web + mcp argocd apps (prod) (#18)

## Summary

ArgoCD Applications + Keycloak clients + sealed secret for forte-drop **web + mcp** (PROD).

## What changed

- **forte-drop** + **forte-drop-mcp** ArgoCD Applications (two-source: forte-helm chart + helm-prod-values).
- **namespace.yaml** — explicit `forte-drop` Namespace at sync-wave -1, `Prune=false` (avoids first-sync race for namespaced resources; doesn't cascade-delete on base removal).
- **keycloak-client-forte-drop** + **keycloak-client-forte-drop-mcp** — labeled config Secrets; the registrar creates the OIDC clients in the `forte` realm within ~2 min.
- **forte-drop-secrets** SealedSecret — UpCloud S3 creds (existing drops bucket) + PG creds + PASSWORD_GATE_SECRET. Consumed by both deployments + the pg-backup CronJob.
- **forte-drop-web PDB** — minAvailable 1 (selector verified against the live forteapp chart's pod labels).
- Wired into `apps/overlays/upc-dev` (NOT base → stays out of upc-prod).

## Post-merge manual step (one-time)

`auth-oidc` SealedSecret for the web sidecar is still commented out — it needs the `client-secret` the Keycloak registrar writes to `forte-drop-oidc-credentials` after first sync:

```bash
CLIENT_SECRET=$(kubectl -n forte-drop get secret forte-drop-oidc-credentials -o jsonpath='{.data.client-secret}' | base64 -d)
kubectl create secret generic auth-oidc -n forte-drop \
  --from-literal=client-secret="$CLIENT_SECRET" \
  --from-literal=cookie-secret="$(openssl rand -hex 32)" \
  --dry-run=client -o yaml > private/auth-oidc.yaml
kubeseal --format=yaml --controller-name=sealed-secrets-controller --controller-namespace=kube-system \
  < private/auth-oidc.yaml > apps/base/forte-drop/auth-oidc-sealed.yaml
# uncomment in kustomization, commit, push
```

## Depends on

- launchpad PR #17 (postgres + namespace via CreateNamespace).
- helm-prod-values forte-drop PR (values).

## Review

- [x] codex: namespace first-sync race → fixed (explicit namespace, sync-wave -1).
- [x] Keycloak registrar unblocked (stale chibisafe/minio config secrets removed; registrar green).

🤖 Generated with Claude Code

Co-authored-by: Sten <sten@Sten-sin-MacBook-Pro.local>
Co-authored-by: Sten <sten@Mac.domain_not_set.invalid>
Co-authored-by: Danijel Simeunovic <danijel.simeunovic@fortedigital.com>
Reviewed-on: #18
Reviewed-by: Danijel Simeunovic <danijel.simeunovic@fortedigital.com>

apps/overlays/upc-dev/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/overlays/upc-dev/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