refactor: flatten skill structure, remove .claude nesting

- Move files from exam/.claude/skills/exam/ to exam/
- Update path references in SKILL.md
- Fix schema path resolution in validate scripts (1 level up instead of 3)

exam/SKILL.md

@@ -21,8 +21,8 @@ examination/
 │       ├── meta.json           # 子主题元信息
 │       ├── fill_blank.json     # 填空题
 │       └── single_choice.json  # 单选题
-└── .claude/skills/exam/
-    ├── SKILL.md                # 本文件
+└── exam/                       # 本 skill 目录
+    ├── SKILL.md
     ├── validate.py             # Python 校验脚本
     └── validate.mjs            # Node.js 校验脚本
 ```
@@ -73,10 +73,10 @@ ENDJSON
 
 ```bash
 # Python (优先)
-python3 .claude/skills/exam/validate.py /tmp/exam_gen.json
+python3 exam/validate.py /tmp/exam_gen.json
 
 # Node.js (备选)
-node .claude/skills/exam/validate.mjs /tmp/exam_gen.json
+node exam/validate.mjs /tmp/exam_gen.json
 ```
 
 - 校验通过 → 继续写入
@@ -115,8 +115,8 @@ node .claude/skills/exam/validate.mjs /tmp/exam_gen.json
 
 两个脚本功能相同，检测可用环境后选用：
 
-- `.claude/skills/exam/validate.py` — 优先用 `jsonschema`，不可用时回退到基础校验
-- `.claude/skills/exam/validate.mjs` — 纯 Node.js 内置模块，无外部依赖
+- `exam/validate.py` — 优先用 `jsonschema`，不可用时回退到基础校验
+- `exam/validate.mjs` — 纯 Node.js 内置模块，无外部依赖
 
 退出码：0=通过，1=有错误，2=用法错误。
 

exam/validate.mjs

@@ -15,7 +15,7 @@ import { fileURLToPath } from "node:url";
 import { createRequire } from "node:module";
 
 const __dirname = dirname(fileURLToPath(import.meta.url));
-const REPO_ROOT = resolve(__dirname, "../../..");
+const REPO_ROOT = resolve(__dirname, "..");
 const SCHEMA_PATH = resolve(REPO_ROOT, "schema/question.schema.json");
 
 function loadJson(path) {

exam/validate.py

@@ -11,9 +11,9 @@ import json
 import sys
 from pathlib import Path
 
-# Resolve schema path relative to repo root (3 levels up from this script)
+# Resolve schema path relative to repo root (1 level up from this script)
 SCRIPT_DIR = Path(__file__).resolve().parent
-REPO_ROOT = SCRIPT_DIR.parent.parent.parent
+REPO_ROOT = SCRIPT_DIR.parent
 SCHEMA_PATH = REPO_ROOT / "schema" / "question.schema.json"