refactor: 重命名 command checker 为 cmd checker 并适配跨平台测试

将 type/configKey 从 "command" 统一为 "cmd"，源码目录 runner/command/ → runner/cmd/，
spec 目录 command-checker/ → cmd-checker/，测试全部改用 bun -e 替代 Unix 系统命令，
归档 cmd-checker-enhancement 变更并同步 delta spec 到主 spec。

probes.example.yaml

@@ -12,7 +12,7 @@ defaults:
   http:
     method: GET
     maxBodyBytes: "10MB"
-  command:
+  cmd:
     maxOutputBytes: "1MB"
 
 targets:
@@ -149,75 +149,74 @@ targets:
     expect:
       status: [200]
 
-  # ========== Command targets ==========
+  # ========== Cmd targets ==========
 
-  - name: "uname 输出匹配"
-    type: command
+  - name: "Bun 版本输出匹配"
+    type: cmd
     group: "系统检查"
-    command:
-      exec: "uname"
-      args: ["-s"]
+    cmd:
+      exec: "bun"
+      args: ["--version"]
     expect:
       exitCode: [0]
       stdout:
-        - match: "^[A-Z][a-z]+$"
+        - match: "^\\d+\\.\\d+\\.\\d+"
 
-  - name: "echo 自定义文本输出"
-    type: command
-    command:
-      exec: "echo"
-      args: ["check ok"]
+  - name: "自定义文本输出"
+    type: cmd
+    cmd:
+      exec: "bun"
+      args: ["-e", "console.log('check ok')"]
     expect:
       stdout:
         - equals: "check ok\n"
       maxDurationMs: 3000
 
-  - name: "ls 目录无 stderr"
-    type: command
-    command:
-      exec: "ls"
-      args: ["/tmp"]
-      cwd: "/"
+  - name: "脚本执行无 stderr"
+    type: cmd
+    cmd:
+      exec: "bun"
+      args: ["-e", "process.stdout.write('ok')"]
     expect:
       exitCode: [0]
       stderr:
         - empty: true
 
-  - name: "date 输出包含年份"
-    type: command
-    command:
-      exec: "date"
-      args: ["+%Y"]
+  - name: "日期脚本输出包含年份"
+    type: cmd
+    cmd:
+      exec: "bun"
+      args: ["-e", "console.log(new Date().getFullYear())"]
     expect:
       stdout:
         - match: "^20\\d{2}\n?$"
 
-  - name: "wc 行数计数"
-    type: command
-    command:
-      exec: "wc"
-      args: ["-l"]
-      cwd: "/etc"
+  - name: "环境变量覆盖"
+    type: cmd
+    cmd:
+      exec: "bun"
+      args: ["-e", "console.log(process.env.LANG ?? '')"]
       env:
         LANG: "C"
     expect:
       stdout:
-        - match: "\\d+"
+        - contains: "C"
 
-  - name: "hostname 非空输出"
-    type: command
-    command:
-      exec: "hostname"
+  - name: "运行平台非空输出"
+    type: cmd
+    cmd:
+      exec: "bun"
+      args: ["-e", "console.log(process.platform)"]
     expect:
       stdout:
         - match: ".+"
 
   - name: "多规则 stdout 顺序校验"
-    type: command
+    type: cmd
     interval: "5m"
-    command:
-      exec: "echo"
-      args: ["version: 2.0.1, status: healthy"]
+    cmd:
+      exec: "bun"
+      args: ["-e", "console.log('version: 2.0.1, status: healthy')"]
     expect:
       stdout:
         - contains: "version:"
@@ -225,11 +224,11 @@ targets:
         - contains: "healthy"
 
   - name: "stderr 内容检查"
-    type: command
-    command:
-      exec: "ls"
-      args: ["/nonexistent-path-checker-test"]
+    type: cmd
+    cmd:
+      exec: "bun"
+      args: ["-e", "process.stderr.write('simulated error\\n'); process.exit(1)"]
     expect:
-      exitCode: [0, 1, 2]
+      exitCode: [1]
       stderr:
-        - contains: "No such file"
+        - contains: "simulated error"