Add Railiance canary chart template

docs/overlay-repo-pattern.md

@@ -97,8 +97,9 @@ Stage 2 candidate.
 
 The chart is the Railiance deployment wrapper. It may start as a thin Helm
 chart around an upstream image and grow only as required by the promotion gates.
-It should keep defaults conservative and route production-specific choices
-through `values/` files.
+Generated charts include stable/canary release identities, Prometheus-compatible
+annotations, HTTP probes, resource limits, isolated canary ingress, and optional
+Traefik weighted routing. Production-specific choices stay in `values/` files.
 
 ### `values/`
 
@@ -112,11 +113,14 @@ Secret values do not belong in these files. Use Kubernetes Secret,
 ExternalSecret, OpenBao, KeyCape, or another approved route and record only the
 reference name.
 
-### `tests/stage1.sh`
+### `tests/stage1.sh` And `tests/stage2-template.sh`
 
 Stage 1 should be runnable without production credentials. The generated script
 performs syntax and Helm rendering checks when the relevant tools are available.
-Workload-specific tests can extend it.
+
+Stage 2 template validation verifies the canary scaffold, stable/canary values,
+Prometheus annotations, rollback labels, and Helm rendering when Helm is
+available. Workload-specific tests can extend either script.
 
 ### `runbooks/rollback.md`
 
@@ -147,8 +151,8 @@ fetch secrets, or push Git remotes.
 1. Generate or update the overlay repo.
 2. Fill in accurate image, namespace, health, dependency, and rollback fields.
 3. Validate `railiance/app.toml` against the schema.
-4. Run `tests/stage1.sh`.
-5. Use later T04-T07 commands to run, deploy, observe, promote, and rollback.
+4. Run `tests/stage1.sh` and `tests/stage2-template.sh`.
+5. Use later T06-T07 commands to deploy, observe, promote, and rollback.
 
 ## Safety Rules