fix(constitution): 修正 QA AI 权限 - 区分'禁止修改'与'禁止读取'

问题：QA AI 无法读取源码和文档，无法编写测试
修正：
- tester.json: projects/*/src/、projects/*/docs/、shared/ 从 forbidden 移至 read_only
- AGENTS.md: QA AI 只读路径补充业务代码、技术文档、共享资源、验收标准
- ai-collab-setup/SKILL.md: 权限矩阵同步更新，QA AI 可读 src/docs/shared

影响：QA AI 现在可以读取源码和文档来编写正确的测试用例

.ai/config/tester.json

@@ -15,16 +15,19 @@
     "review/*/feedback/"
   ],
   "read_only_paths": [
-    "review/*/task.md",
-    "docs/",
-    "data/"
-  ],
-  "forbidden_paths": [
     "projects/*/src/",
     "projects/*/docs/",
+    "docs/",
+    "data/",
     "shared/",
+    "review/*/task.md",
+    "review/*/acceptance.md"
+  ],
+  "forbidden_paths": [
+    ".ai/",
+    "tools/",
     "review/*/impact.md",
-    "tools/"
+    "review/*/feedback/"
   ],
   "prompt_templates": {
     "testing": ".ai/prompts/testing/"