refactor: 清理废弃字段，同步 Schema 定义

- Agent 文件：删除 downloads、rating、ratingCount、installStatus、source
- Skill 文件：删除 downloads、rating、ratingCount、installStatus、source、version
- Skill 文件：新增 files 字段，指向配置文件路径
- 字段说明：source 和 installStatus 改为运行时计算

Refs: desirecore/desirecore#field-recovery

agents/task-master/agent.json

@@ -8,7 +8,13 @@
   "shortDesc": "智能任务规划与追踪专家，帮你建立可持续的执行系统",
   "fullDesc": "任务管家是你的个人效率教练。它不只是记录待办事项，而是通过智能分析帮你识别关键任务、建立优先级矩阵、设置合理的里程碑提醒。\n\n核心能力包括：\n- 任务拆解：将大目标分解为可执行的小步骤\n- 优先级排序：基于 Eisenhower 矩阵的智能建议\n- 时间估算：基于历史数据预测完成时间\n- 进度追踪：可视化展示项目健康度\n- 复盘总结：自动生成周/月度效率报告",
   "category": "productivity",
-  "tags": ["任务管理", "GTD", "番茄工作法", "效率", "时间管理"],
+  "tags": [
+    "任务管理",
+    "GTD",
+    "番茄工作法",
+    "效率",
+    "时间管理"
+  ],
   "version": "2.3.1",
   "latestVersion": "2.3.1",
   "updatedAt": "2025-02-10",
@@ -16,14 +22,20 @@
     "name": "DesireCore Official",
     "verified": true
   },
-  "downloads": 45820,
-  "rating": 4.8,
-  "ratingCount": 1247,
-  "installStatus": "not_installed",
   "persona": {
     "role": "效率顾问与任务规划师",
-    "traits": ["条理清晰", "执行力强", "善于拆解复杂问题", "鼓励但不施压"],
-    "tools": ["task_scheduler", "reminder_api", "time_tracker", "progress_visualizer"]
+    "traits": [
+      "条理清晰",
+      "执行力强",
+      "善于拆解复杂问题",
+      "鼓励但不施压"
+    ],
+    "tools": [
+      "task_scheduler",
+      "reminder_api",
+      "time_tracker",
+      "progress_visualizer"
+    ]
   },
   "changelog": "v2.3.1: 新增时间块规划功能，优化与日历应用的同步稳定性"
 }