feat(arch-ai): 新增 Arch AI（架构AI）角色，升级为'1 人+3AI'协作模式

新增:
- .ai/config/architect.json - Arch AI 配置文件（最高 AI 权限）
- .ai/prompts/architecture/ - 架构设计提示词目录

修改:
- AGENTS.md: 新增 Arch AI 角色定义，权限矩阵增加 Arch AI 列
- workflow.json: 工作流从 4 阶段扩展为 5 阶段（新增架构设计阶段）
- ai-collab-setup/SKILL.md: 全面支持 3 角色架构，版本升至 v3.0
- resume-context/SKILL.md: 架构模式改为 Arch AI，版本升至 v3.0

工作流变更:
需求分析(Arch AI) → 架构设计(Arch AI) → 开发实现(Dev AI) → 测试验证(QA AI) → 验收确认(人类)

.ai/config/workflow.json

@@ -1,17 +1,23 @@
 {
   "workflow": "human-ai-collaboration",
-  "roles": ["human", "dev-ai", "qa-ai"],
+  "roles": ["human", "arch-ai", "dev-ai", "qa-ai"],
   "stages": [
     {
       "name": "需求分析",
-      "actor": "human",
-      "output": "review/{task_id}/task.md"
+      "actor": "arch-ai",
+      "output": ["docs/01_产品需求/PRD.md", "review/{task_id}/task.md"]
+    },
+    {
+      "name": "架构设计",
+      "actor": "arch-ai",
+      "input": ["docs/01_产品需求/PRD.md", "review/{task_id}/task.md"],
+      "output": ["docs/02_系统架构/", "review/{task_id}/impact.md", "review/{task_id}/acceptance.md"]
     },
     {
       "name": "开发实现",
       "actor": "dev-ai",
-      "input": "review/{task_id}/task.md",
-      "output": ["projects/*/src/", "projects/*/docs/", "review/{task_id}/impact.md", "review/{task_id}/acceptance.md"]
+      "input": ["review/{task_id}/task.md", "review/{task_id}/acceptance.md"],
+      "output": ["projects/*/src/", "projects/*/docs/"]
     },
     {
       "name": "测试验证",