refactor: one self-contained folder per platform service

Each platform/apps/<service>/ now holds its own application.yaml
(multi-source: chart + values + raw-manifest extras), values.yaml, and
any extra manifests (HTTPRoute, RBAC, ClusterSecretStore) together,
replacing the split apps/*.yaml + manifests/*/ + separate *-config
Application pattern.

Root platform-app.yaml now recurses platform/apps/*/application.yaml
only. Extras get a resource-level sync-wave (1) so they still land
after their service's Helm chart within the same Application sync.

Also adds an HTTPRoute for vault (vault.fireflylab.local) - exposed
same as every other service here, accepted as LAN-only exposure.

platform/apps/headlamp/application.yaml

@@ -0,0 +1,34 @@
+apiVersion: argoproj.io/v1alpha1
+kind: Application
+metadata:
+  name: headlamp
+  namespace: argocd
+  annotations:
+    argocd.argoproj.io/sync-wave: "0"
+spec:
+  project: default
+  sources:
+    - repoURL: https://kubernetes-sigs.github.io/headlamp/
+      chart: headlamp
+      targetRevision: "0.31.0"  # TODO: verify latest via `helm search repo headlamp/headlamp --versions`
+      helm:
+        valueFiles:
+          - $values/platform/apps/headlamp/values.yaml
+    - repoURL: https://gitea.fireflylab.cc/duynguyen/cluster-platform.git
+      targetRevision: main
+      ref: values
+    - repoURL: https://gitea.fireflylab.cc/duynguyen/cluster-platform.git
+      targetRevision: main
+      path: platform/apps/headlamp
+      directory:
+        exclude: "{application.yaml,values.yaml}"
+  destination:
+    server: https://kubernetes.default.svc
+    namespace: headlamp
+  syncPolicy:
+    automated:
+      prune: true
+      selfHeal: true
+    syncOptions:
+      - CreateNamespace=true
+      - SkipDryRunOnMissingResource=true