feat: 添加媒体播放功能，支持基于短时效token的播放入口及相关API接口

backend/docs/swagger.yaml

@@ -449,9 +449,10 @@ definitions:
   dto.ContentAssetsResponse:
     properties:
       assets:
-        description: Assets is the list of media assets for the requested role (preview/main).
+        description: Assets is the list of playable assets for the requested role
+          (preview/main).
         items:
-          $ref: '#/definitions/models.MediaAsset'
+          $ref: '#/definitions/dto.ContentPlayableAsset'
         type: array
       content:
         allOf:
@@ -512,6 +513,26 @@ definitions:
         description: Price is the current price settings for the content (may be nil
           if not set).
     type: object
+  dto.ContentPlayableAsset:
+    properties:
+      asset_id:
+        type: integer
+      expires_at:
+        description: ExpiresAt indicates when PlayURL/token expires; optional.
+        type: string
+      meta:
+        description: Meta is a display-safe whitelist (currently passthrough JSON);
+          optional.
+        items:
+          type: integer
+        type: array
+      play_url:
+        description: PlayURL is a short-lived URL; do NOT expose bucket/object_key
+          directly.
+        type: string
+      type:
+        $ref: '#/definitions/consts.MediaAssetType'
+    type: object
   dto.ContentPriceUpsertForm:
     properties:
       currency:
@@ -2855,6 +2876,27 @@ paths:
       summary: 当前租户余额流水（分页）
       tags:
       - Tenant
+  /t/{tenantCode}/v1/media/play:
+    get:
+      consumes:
+      - application/json
+      parameters:
+      - description: Tenant Code
+        in: path
+        name: tenantCode
+        required: true
+        type: string
+      - description: Play token
+        in: query
+        name: token
+        required: true
+        type: string
+      produces:
+      - application/json
+      responses: {}
+      summary: 媒体播放入口（短时效 token）
+      tags:
+      - TenantMedia
   /t/{tenantCode}/v1/orders:
     get:
       consumes: