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/kube-prometheus-stack/values.yaml

@@ -0,0 +1,26 @@
+grafana:
+  persistence:
+    enabled: true
+    storageClassName: nfs-delete
+    size: 5Gi
+
+prometheus:
+  prometheusSpec:
+    storageSpec:
+      volumeClaimTemplate:
+        spec:
+          storageClassName: nfs-delete
+          resources:
+            requests:
+              storage: 20Gi
+    retention: 15d
+
+alertmanager:
+  alertmanagerSpec:
+    storage:
+      volumeClaimTemplate:
+        spec:
+          storageClassName: nfs-delete
+          resources:
+            requests:
+              storage: 2Gi