fix: Instagram 热点过滤低互动内容并按点赞数排序

- 适配器过滤 like_count < 100 的低质量内容，按点赞数降序排列
- 后端 dev/start 脚本添加 --env-file=.env 自动加载环境变量

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/backend/package.json

@@ -4,8 +4,8 @@
   "private": true,
   "type": "module",
   "scripts": {
-    "dev": "tsx watch src/index.ts",
+    "dev": "tsx watch --env-file=.env src/index.ts",
-    "start": "tsx src/index.ts",
+    "start": "tsx --env-file=.env src/index.ts",
     "test": "vitest run",
     "test:watch": "vitest",
     "test:coverage": "vitest run --coverage"

packages/backend/src/lib/adapters/instagram.test.ts

@@ -58,7 +58,7 @@ describe("InstagramAdapter", () => {
                     code: "SEC001",
                     caption: "Section post",
                     user: { username: "user1" },
-                    like_count: 1000,
+                    like_count: 5000,
                   },
                 ],
               },
@@ -87,6 +87,7 @@ describe("InstagramAdapter", () => {
             code: "cap-obj",
             caption: { text: "Caption from object" },
             user: { username: "test" },
+            like_count: 500,
           },
         ],
       });
@@ -102,6 +103,7 @@ describe("InstagramAdapter", () => {
             code: "cap-str",
             caption: "String caption",
             user: { username: "test" },
+            like_count: 500,
           },
         ],
       });
@@ -117,6 +119,7 @@ describe("InstagramAdapter", () => {
             code: "cap-null",
             caption: null,
             user: { username: "test" },
+            like_count: 500,
           },
         ],
       });
@@ -132,6 +135,7 @@ describe("InstagramAdapter", () => {
             code: "thumb-test",
             thumbnail_url: "https://ig.com/thumb.jpg",
             user: { username: "test" },
+            like_count: 500,
           },
         ],
       });
@@ -139,6 +143,22 @@ describe("InstagramAdapter", () => {
       const items = await adapter.fetchTrending(20);
       expect(items[0].cover_url).toBe("https://ig.com/thumb.jpg");
     });
+
+    it("filters out low-engagement items and sorts by likes", async () => {
+      mockFetch.mockResolvedValueOnce({
+        items: [
+          { code: "low", caption: "Low", user: { username: "a" }, like_count: 5 },
+          { code: "high", caption: "High", user: { username: "b" }, like_count: 10000 },
+          { code: "mid", caption: "Mid", user: { username: "c" }, like_count: 500 },
+          { code: "none", caption: "None", user: { username: "d" } },
+        ],
+      });
+
+      const items = await adapter.fetchTrending(20);
+      expect(items).toHaveLength(2);
+      expect(items[0].id).toBe("high");
+      expect(items[1].id).toBe("mid");
+    });
   });
 
   describe("fetchDetail", () => {

packages/backend/src/lib/adapters/instagram.ts

@@ -34,10 +34,12 @@ export class InstagramAdapter implements PlatformAdapter {
     }
 
     return items
-      .slice(0, count)
       .map((item: unknown, index: number) =>
         this.mapToContentItem(item as Record<string, unknown>, index)
-      );
+      )
+      .filter((item) => item.like_count != null && item.like_count >= 100)
+      .sort((a, b) => (b.like_count ?? 0) - (a.like_count ?? 0))
+      .slice(0, count);
   }
 
   async fetchDetail(id: string): Promise<ContentItem> {