fix: 讯飞鉴权HTTP兼容+AI段落紧凑+对话模式JSON降级

- ReportEditor: 讯飞鉴权改用crypto-js HMAC-SHA256，兼容HTTP非安全环境
- defaultContent.ts+ReportEditor: AI区域<p>标签去掉margin-bottom，段落紧密排布
- ReportEditor: 纯对话模式下JSON解析失败时降级为直接文本回复
- ReportEditor: 对话模式systemPrompt强化JSON格式约束
- deps: 新增crypto-js用于讯飞鉴权

package.json

@@ -13,7 +13,9 @@
   "dependencies": {
     "@google/genai": "^1.29.0",
     "@tailwindcss/vite": "^4.1.14",
+    "@types/crypto-js": "^4.2.2",
     "@vitejs/plugin-react": "^5.0.4",
+    "crypto-js": "^4.2.0",
     "diff": "^9.0.0",
     "dotenv": "^17.2.3",
     "express": "^4.21.2",