feat(assets): add searchable media library and verified orphan cleanup

internal/api/openapi.json

@@ -737,6 +737,14 @@
             "schema": {
               "type": "string"
             }
+          },
+          {
+            "name": "folder",
+            "in": "query",
+            "description": "文件夹图片管理上传目标，空字符串表示根目录；与 note 互斥",
+            "schema": {
+              "type": "string"
+            }
           }
         ],
         "requestBody": {
@@ -2449,6 +2457,42 @@
           }
         }
       }
+    },
+    "/assets/cleanup": {
+      "post": {
+        "summary": "重新核对全库引用和有效分享后，将孤立图片移入回收站",
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": {
+                "type": "object",
+                "required": [
+                  "paths"
+                ],
+                "properties": {
+                  "paths": {
+                    "type": "array",
+                    "minItems": 1,
+                    "maxItems": 1000,
+                    "items": {
+                      "type": "string"
+                    }
+                  }
+                }
+              }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "已移入回收站的图片及跳过原因"
+          },
+          "400": {
+            "description": "请求无效，或笔记元数据异常，无法确认引用"
+          }
+        }
+      }
     }
   },
   "components": {