Deploy sales/dev dataplane (Layer 2), mirroring catalog/customers/payments

Real Konnect Control Plane 84a3dd19-7daf-47e6-84ea-9ad5966b91a6, PAT
in Vault (kong-v2/sales/dev/konnect-pat). Replaces the TODO stubs
with the proven gateway-kustomization.yaml + externalsecret.yaml +
policies-kustomization.yaml pattern. JWT_AUDIENCE_WHITELIST includes
mcp-sales from the start since Layer 3 (REST + MCP) was built the
same session — see STATUS.md section 22.

README.md

@@ -1,10 +1,37 @@
 # dataplane-sales
 
 Layer 2 (Gateway infrastructure) for the **sales** bounded context
-(domain team: sales). `DataPlane`, `KonnectExtension`, certs (cert-manager),
-secrets (External Secrets Operator) — one Control Plane per environment,
-referenced by ID (created by `../konnect-platform`, never recreated here).
+(domain team: sales) — one Control Plane per environment, referenced by
+ID (created manually in Konnect for now, never recreated here:
+`84a3dd19-7daf-47e6-84ea-9ad5966b91a6` for `dev`).
 
-Content is generated and PR'd automatically when the matching Control
-Plane is created via the self-service flow in `../konnect-platform` —
-never hand-edited directly.
+Same `gateway-kustomization.yaml` / `externalsecret.yaml` /
+`policies-kustomization.yaml` three-file pattern as `dataplane-catalog`/
+`dataplane-customers`/`dataplane-payments` — see `dataplane-catalog/README.md`
+for the full explanation of each file's role, identical here, not
+repeated. Actual resource template lives in
+`../k8s-platform/dataplane-template/` and
+`../k8s-platform/dataplane-globalpolicy-template/`, this repo only holds
+what's specific to `dev/api-gateway/`.
+
+**IdP**: `https://keycloak.sttlab.local/realms/classic-models` (local
+in-cluster Keycloak), platform-wide default — see `../STATUS.md` sections
+15/16. `JWT_AUDIENCE_WHITELIST` set to `["sales-api", "mcp-sales"]` from
+the start (both the REST and MCP layers were built in the same pass as
+this Layer 2 deploy — see `../STATUS.md` section 22).
+
+**Only `dev/` is real.** `staging/api-gateway/` and `prod/api-gateway/`
+still hold the original TODO placeholder files, not converted, not
+deployed, no Control Plane created for them yet.
+
+**Layer 3 is real here, unlike some other domains at their Layer-2-only
+stage**: `../sales-api` (REST + MCP) was built and deployed the same
+session as this Layer 2 repo — `Gateway sales-dev`: `Programmed: True`,
+DNS entry added to `coredns-custom` (`sales-dev.sttlab.local` →
+the `dataplane-ingress-sales-dev-*` Service `ClusterIP`, same manual
+per-domain step documented in `../STATUS.md` section 17), all REST/MCP
+routes smoke-tested (`401`, not `404`/`502`).
+
+Self-service pipeline (`../konnect-platform` generating this content
+automatically) does not exist yet — still a stub per `../STATUS.md`.
+Everything here is hand-maintained.