chore(skill): 安全扫描警告清零 + 加入 skill-gate CI

- scan-skill.sh: loopback 不算风险、命中走允许清单
- 11 个文件的 /Users/<机器名> 绝对路径去环境化（脚本 $HOME、文档 ~）
- 允许清单登记运维环境地址与示例占位符（非凭据），附理由
- scan: 57 warns -> 0 warns / 0 high
- 新增 .gitea/workflows/skill-gate.yml（validate --strict + scan + catalog --check + 测试）

hooks/README.md

@@ -23,7 +23,7 @@
         "hooks": [
           {
             "type": "command",
-            "command": "/Users/donglinlai/coding/qiudl/ai-proj-helper/hooks/session-context.sh",
+            "command": "~/coding/qiudl/ai-proj-helper/hooks/session-context.sh",
             "timeout": 10
           }
         ]
@@ -35,7 +35,7 @@
         "hooks": [
           {
             "type": "command",
-            "command": "/Users/donglinlai/coding/qiudl/ai-proj-helper/hooks/pre-tool-confirm.sh",
+            "command": "~/coding/qiudl/ai-proj-helper/hooks/pre-tool-confirm.sh",
             "timeout": 30
           }
         ]
@@ -48,7 +48,7 @@
 ### 方式 2：一键安装脚本
 
 ```bash
-bash /Users/donglinlai/coding/qiudl/ai-proj-helper/hooks/install.sh
+bash ~/coding/qiudl/ai-proj-helper/hooks/install.sh
 ```
 
 ## 验证