feat(ECR-014): MembershipPlan 套餐配置并 Closed

membership_plans 表、admin 套餐页、Grant/CreateOrder 读表；
Loop continuous 自动 Approve/Closed。Next：ECR-015 RedemptionCode。

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

proto/openapi.yaml

@@ -242,6 +242,60 @@ paths:
         '401':
           description: Unauthorized
 
+  /api/v1/admin/membership-plans:
+    get:
+      tags: [admin]
+      summary: List membership plans
+      description: Requires admin.membership.plans.read
+      responses:
+        '200':
+          description: OK
+        '403':
+          description: Forbidden
+
+  /api/v1/admin/membership-plans/{code}:
+    get:
+      tags: [admin]
+      summary: Get membership plan
+      parameters:
+        - in: path
+          name: code
+          required: true
+          schema: { type: string }
+      responses:
+        '200':
+          description: OK
+        '404':
+          description: Not found
+    put:
+      tags: [admin]
+      summary: Update membership plan
+      description: Requires admin.membership.plans.write
+      parameters:
+        - in: path
+          name: code
+          required: true
+          schema: { type: string }
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              type: object
+              required: [title, duration_days, amount_cents]
+              properties:
+                title: { type: string }
+                duration_days: { type: integer }
+                amount_cents: { type: integer }
+                active: { type: boolean }
+      responses:
+        '200':
+          description: OK
+        '400':
+          description: Invalid
+        '403':
+          description: Forbidden
+
   /api/v1/admin/orders:
     get:
       tags: [admin]