feat(ECR-024): OpsCMS Banner 只读并 Closed

运营横幅目录（ops_banners + admin /cms），锁定 024–040 全队列。

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/CONTRACT_DIFF/ECR-024.yaml

@@ -0,0 +1,22 @@
+ecr: ECR-024
+capability: OpsCMS
+bounded_context: Ops_CMS_NoUGC
+parent: WAVE0-FROZEN
+predecessor: ECR-023
+change:
+  type: additive
+breaking_change: false
+migration_required: true
+compatibility_notes: >
+  Adds Banner read catalog. Forbidden: UGC / real payment.
+
+apis:
+  - method: GET
+    path: /api/v1/admin/cms/banners
+    change: added
+  - method: GET
+    path: /api/v1/admin/cms/banners/{id}
+    change: added
+perms:
+  - code: admin.cms.read
+    change: added