Build sales-api REST + MCP layers (Layer 3), full build in one pass

14 routes: Order (single key, full CRUD + order-details sub-resource)
and Orderdetail (composite key ordernumber+productcode, own
top-level resource, mirrors backend's own URL structure). MCP layer
built with the corrected single-route pattern from the start
(STATUS.md section 18) — 7 tools, list/get read-only for all 5
roles, create-order/create-orderdetail for admin+customer+support
(verified against OrderPermission/OrderScopedPermission.check() —
support gets an unconditional class-level pass, the status-only
restriction is object-level and doesn't apply to create).

Keycloak (local): sales-api-audience + mcp-sales-audience client
scopes, sales-api + mcp-sales resource clients, attached to the
broker and librechat respectively. Deploy key and broker secret
reused/mirrored from catalog-api and the live broker client, same
pattern as customers-api/payments-api.

dev/externalsecret.yaml

@@ -0,0 +1,25 @@
+apiVersion: external-secrets.io/v1
+kind: ExternalSecret
+metadata:
+  name: sales-api-git-auth
+  namespace: sales
+spec:
+  refreshInterval: 1h
+  secretStoreRef:
+    kind: ClusterSecretStore
+    name: vault-kong-v2
+  target:
+    name: sales-api-git-auth
+  data:
+    - secretKey: identity
+      remoteRef:
+        key: kong-v2/sales-api/git-deploy-key
+        property: identity
+    - secretKey: identity.pub
+      remoteRef:
+        key: kong-v2/sales-api/git-deploy-key
+        property: identity.pub
+    - secretKey: known_hosts
+      remoteRef:
+        key: kong-v2/sales-api/git-deploy-key
+        property: known_hosts