refactor: 将 checker normalize 职责下沉到各 runner 目录

- 新增 CheckerDefinition.normalize 必需方法，typecheck 兜底遗漏实现
- 新增 expect/normalize.ts 共享 helper（compactExpect、normalizeValue、
  normalizeContent、normalizeKeyed）
- 为 HTTP、Cmd、DB、TCP、UDP、ICMP、LLM、WS、DNS 各新增独立 normalize.ts
- 简化 normalizer.ts：删除所有 checker type switch，改为 registry 委托
- 修复 DNS authoring 简写 bug：durationMs、valueCount、result 等字段
  现可通过完整加载链路
- 新增 DNS 回归测试和 registry 级合同测试
- 更新 docs/development/checker.md：补充 normalize 规范、文件结构、
  测试要求和 checklist

tests/server/checker/config-contract/validate.test.ts

@@ -1,6 +1,7 @@
 import Ajv from "ajv";
 import { describe, expect, test } from "bun:test";
 
+import { normalizeAuthoringConfig } from "../../../../src/server/checker/normalizer";
 import { createDefaultCheckerRegistry } from "../../../../src/server/checker/runner";
 import { createProbeConfigJsonSchema } from "../../../../src/server/checker/schema/export";
 import { formatConfigIssues, issue } from "../../../../src/server/checker/schema/issues";
@@ -274,4 +275,115 @@ describe("config contract", () => {
       }),
     ).toBe(false);
   });
+
+  test("所有 checker 的 authoring ValueMatcher 简写经 normalize 后通过 normalized contract 校验", () => {
+    const authoringShorthandExamples: Record<string, object> = {
+      cmd: {
+        targets: [
+          {
+            cmd: { exec: "echo hello" },
+            expect: { durationMs: 1000 },
+            id: "cmd-test",
+            type: "cmd",
+          },
+        ],
+      },
+      db: {
+        targets: [
+          {
+            db: { url: "sqlite://:memory:" },
+            expect: { durationMs: 2000 },
+            id: "db-test",
+            type: "db",
+          },
+        ],
+      },
+      dns: {
+        targets: [
+          {
+            dns: { name: "example.com", resolver: "system" },
+            expect: { durationMs: 500 },
+            id: "dns-test",
+            type: "dns",
+          },
+        ],
+      },
+      http: {
+        targets: [
+          {
+            expect: { durationMs: 5000 },
+            http: { url: "https://example.com" },
+            id: "http-test",
+            type: "http",
+          },
+        ],
+      },
+      icmp: {
+        targets: [
+          {
+            expect: { packetLossPercent: 0 },
+            icmp: { host: "example.com" },
+            id: "icmp-test",
+            type: "icmp",
+          },
+        ],
+      },
+      llm: {
+        targets: [
+          {
+            expect: { durationMs: 10000 },
+            id: "llm-test",
+            llm: {
+              model: "gpt-4o-mini",
+              prompt: "ping",
+              provider: "openai",
+              url: "https://example.com/v1/chat/completions",
+            },
+            type: "llm",
+          },
+        ],
+      },
+      tcp: {
+        targets: [
+          {
+            expect: { durationMs: 3000 },
+            id: "tcp-test",
+            tcp: { host: "example.com", port: 80 },
+            type: "tcp",
+          },
+        ],
+      },
+      udp: {
+        targets: [
+          {
+            expect: { durationMs: 1000 },
+            id: "udp-test",
+            type: "udp",
+            udp: { host: "example.com", port: 53 },
+          },
+        ],
+      },
+      ws: {
+        targets: [
+          {
+            expect: { durationMs: 5000 },
+            id: "ws-test",
+            type: "ws",
+            ws: { url: "wss://example.com/ws" },
+          },
+        ],
+      },
+    };
+
+    for (const [type, config] of Object.entries(authoringShorthandExamples)) {
+      const normalizeResult = normalizeAuthoringConfig(config, createDefaultCheckerRegistry());
+      expect(normalizeResult.issues).toHaveLength(0);
+      const contract = validateProbeConfigContract(normalizeResult.config, createDefaultCheckerRegistry());
+      expect(contract.config).not.toBeNull();
+      expect(
+        contract.issues,
+        `Checker "${type}" authoring shorthand should pass normalized contract, got issues: ${JSON.stringify(contract.issues.map((i) => `${i.path}: ${i.message}`))}`,
+      ).toHaveLength(0);
+    }
+  });
 });