feat(console): CHV executor option in dispatch/env selectors + experimental note in detail/list

- DispatchSection: add cloud-hypervisor option (labelled experimental,
  default off); default stays docker; hint states a KVM-host CHV worker
  must claim the task (otherwise it stays queued; attachments are
  rejected by the backend at creation) and that the frontend only passes
  the executor value through, never bypassing the backend allowlist.
- EnvSection: same option, because the backend env-create allowlist
  (local/docker/cloud-hypervisor) does allow it; note states env
  allowlist excludes cloud.
- TaskListSection: add cloud-hypervisor to the executor filter so CHV
  tasks are findable; list rows already showed executor.
- TaskDetailPanel: pure display note for cloud-hypervisor tasks
  (experimental, default off, no VM controls); detail already showed
  executor from the task API.
- README: document the CHV console entry, experimental marking, and
  verbatim backend-error display.
- Rebuilt cloud/console.html from src (tsc + vite single-file build);
  no backend change: executor is already returned by _task_to_dict.

cloud/console-react/src/sections/EnvSection.tsx

@@ -31,10 +31,11 @@ export default function EnvSection() {
         <input type="text" placeholder="新环境名" value={name} onChange={(e) => setName(e.target.value)} />
         <input type="text" placeholder="分支（可选，空=默认分支）" value={branch} onChange={(e) => setBranch(e.target.value)} />
         <select aria-label="新环境执行器" value={executor} onChange={(e) => setExecutor(e.target.value)}>
-          <option value="">执行器：不限</option><option value="local">local</option><option value="docker">docker</option>
+          <option value="">执行器：不限</option><option value="local">local</option><option value="docker">docker</option><option value="cloud-hypervisor">cloud-hypervisor（实验，默认关闭）</option>
         </select>
         <button onClick={async () => { await ctx.createEnv(name, branch, executor); setName(""); setBranch(""); }}>新建环境</button>
       </Bar>
+      {executor === "cloud-hypervisor" ? <div className="muted">实验执行器，默认关闭：环境创建白名单同样允许 cloud-hypervisor（后端环境接口 allowlist：local / docker / cloud-hypervisor，不含 cloud）；仍需后端有 KVM 宿主上的 CHV worker 才会认领，否则任务排队。前端只传值，不绕过后端白名单。</div> : null}
       <span className="muted">{ctx.envMsg}</span>
     </Card>
   );