refactor: ICMP checker type 从 ping 统一改为 icmp，修复前端 UI 细节

- ICMP checker 的 type/configKey/YAML 配置键/接口属性名从 ping 改为 icmp
- IcmpChecker 添加 platform 构造函数注入，修复 Windows 测试兼容性
- 前端 target 表格延迟列优化：标题简化为「延迟」，单位下移到单元格，宽度 80px
- Drawer 概览页 Descriptions 添加 tableLayout=auto 收窄 label 宽度
- 同步更新 README.md、DEVELOPMENT.md、probes.example.yaml、JSON Schema 和全部测试

tests/server/checker/runner/registry.test.ts

@@ -67,8 +67,8 @@ describe("CheckerRegistry", () => {
     const second = createDefaultCheckerRegistry();
     first.register(createChecker("custom"));
 
-    expect(first.supportedTypes).toEqual(["http", "cmd", "db", "tcp", "ping", "udp", "llm", "custom"]);
-    expect(second.supportedTypes).toEqual(["http", "cmd", "db", "tcp", "ping", "udp", "llm"]);
+    expect(first.supportedTypes).toEqual(["http", "cmd", "db", "tcp", "icmp", "udp", "llm", "custom"]);
+    expect(second.supportedTypes).toEqual(["http", "cmd", "db", "tcp", "icmp", "udp", "llm"]);
     expect(
       first.definitions.every(
         (checker) => checker.schemas.config && checker.schemas.defaults && checker.schemas.expect,
@@ -76,9 +76,9 @@ describe("CheckerRegistry", () => {
     ).toBe(true);
   });
 
-  test("默认 registry 注册 ping type", () => {
+  test("默认 registry 注册 icmp type", () => {
     const registry = createDefaultCheckerRegistry();
-    expect(registry.supportedTypes).toContain("ping");
-    expect(registry.get("ping").configKey).toBe("ping");
+    expect(registry.supportedTypes).toContain("icmp");
+    expect(registry.get("icmp").configKey).toBe("icmp");
   });
 });