feat: 重构配置校验为 TypeBox + Ajv + semantic validator，严格禁止未知字段

- 新增 config-contract 模块（TypeBox fragments、Ajv 契约校验、ConfigValidationIssue）
- CheckerDefinition 扩展为含 configKey、schemas、validate 的完整插件接口
- HTTP/Command 各自维护 contract.ts + validate.ts，校验从 resolve 中分离
- resolve 不再承担校验，只做默认值合并和路径/单位解析
- config-loader 流程: unknown → RawProbeConfig → ValidatedProbeConfig → ResolvedConfig
- 导出 probe-config.schema.json，新增 schema/schema:check 脚本
- 更新 DEVELOPMENT.md 新增 1.7 开发新 Checker 完整指引
- 同步更新 4 个 main specs（probe-config、command-checker、expect-body-checkers、checker-runner-abstraction）

package.json

@@ -9,7 +9,9 @@
     "build": "bun run scripts/build.ts",
     "lint": "eslint .",
     "format": "prettier . --write",
-    "check": "bun run typecheck && bun run lint && bun test",
+    "schema": "bun run scripts/generate-config-schema.ts",
+    "schema:check": "bun run scripts/generate-config-schema.ts --check",
+    "check": "bun run schema:check && bun run typecheck && bun run lint && bun test",
     "verify": "bun run check && bun run build && bun run test:smoke",
     "test": "bun test",
     "test:smoke": "bun run scripts/smoke.ts",
@@ -42,8 +44,10 @@
     "vite": "^8.0.11"
   },
   "dependencies": {
+    "@sinclair/typebox": "^0.34.49",
     "@tanstack/react-query": "^5.100.10",
     "@xmldom/xmldom": "^0.9.10",
+    "ajv": "^8.20.0",
     "cheerio": "^1.2.0",
     "es-toolkit": "^1.46.1",
     "react": "^19.2.6",