Use canonical Modal manifest schema

Author: anth-volk

docs/engineering/skills/modal-release-prs.md

@@ -84,6 +84,13 @@ package version references, or release validation. Those countries may still be
 served by the worker, but their package versions must not control a Modal
 release.
 
+The canonical manifest schema version is `1`. Runtime code should validate that
+stored manifests already match this schema; do not add legacy normalization to
+the gateway, release updater, or active-app discovery paths. The manifest
+rewrite command is the only bridge from older stored shapes: it copies the old
+`current` and `frontier` app references into canonical schema version `1`,
+drops retired history, and removes non-release package keys.
+
 Manual workflow dispatch exposes the same `new_app_target`,
 `promote_existing_frontier`, and `cleanup_target` settings as the PR-body YAML
 block. The deploy workflow and Modal images use Python 3.13.

policyengine_household_api/modal_release/gateway.py

@@ -11,7 +11,7 @@
     MANIFEST_DICT_KEY,
     MANIFEST_DICT_NAME,
     empty_manifest,
-    normalize_manifest,
+    validate_manifest,
 )
 
 
@@ -45,7 +45,7 @@ def liveness_check() -> Response:
     @app.get("/readiness_check")
     def readiness_check() -> Response:
         manifest = load_manifest()
-        if not normalize_manifest(manifest).get("current"):
+        if not validate_manifest(manifest).get("current"):
             return jsonify(
                 {
                     "status": "error",
@@ -56,14 +56,14 @@ def readiness_check() -> Response:
 
     @app.get("/versions")
     def versions() -> Response:
-        return jsonify(normalize_manifest(load_manifest()))
+        return jsonify(validate_manifest(load_manifest()))
 
     @app.get("/versions/<country_id>")
     def country_versions(country_id: str) -> Response:
         if country_id not in COUNTRIES:
             return _json_error(f"Unsupported country `{country_id}`", 404)
 
-        manifest = normalize_manifest(load_manifest())
+        manifest = validate_manifest(load_manifest())
         country_versions = {}
         for channel in ("current", "frontier"):
             app_reference = manifest.get(channel)
@@ -88,7 +88,7 @@ def route_request(path: str) -> Response:
         body = request.get_data()
 
         try:
-            manifest = normalize_manifest(load_manifest())
+            manifest = validate_manifest(load_manifest())
             if country_id and endpoint in VERSIONED_ENDPOINTS:
                 body, requested_version = _extract_requested_version(body)
             else:
@@ -119,7 +119,7 @@ def load_modal_manifest() -> dict[str, Any]:
         )
     except NotFoundError:
         return empty_manifest()
-    return normalize_manifest(manifest_dict.get(MANIFEST_DICT_KEY))
+    return validate_manifest(manifest_dict.get(MANIFEST_DICT_KEY))
 
 
 def resolve_app_for_request(