chore(k8s): 下线 K8s 后端形态，移除依赖 @kubernetes/client-node

生产形态是单机 local（DEFAULT_DEPLOY_MODE=local，env 未覆盖）⇒ K8s 分支
在 local 下本来不可达；且该形态与官方 dsh 基座、插件体系均无关
=> 整体下线，并移除该形态唯一的第三方依赖。

移除（备份在 D:/github/_dsh_shenxian_K8s后端备份_20260915/，含还原命令与
「集群化方案要复用的模板清单」）：
  src/supervisor/{k8s-spawner,leader,reconcile}.ts
  src/fs/k8s-user-fs.ts · src/tcp-bridge.ts · src/web/file-service.ts
  test/{k8s-spawner,leader}.test.mjs · scripts/smoke-file-service.mjs

改写调用方：cli.ts（5 条 import / 选主块 / file-service 与 tcp-bridge 两个
子命令 / dispatch / HELP）、web/server.ts（改为 fail-loud 守卫 + 恒用
LocalSpawner）、fs/provider.ts（只留 LocalUserFs）、package.json（测试与
smoke 入口），外加 3 处指向已删类型的悬空 JSDoc。

保留（集群化方案列为未来可选）：deploy/ · poc/01-04 · Dockerfile.dsh ·
docs/k8s*.md（已加「代码已下线」状态横幅）· config.ts 的 K8s 配置字段与
DeployMode 联合类型。

验证：tsc --noEmit exit 0；npm test 36 测试 / 35 通过 / 0 失败 / 1 跳过；
npm run verify exit 0；依赖与被删符号全仓 0 命中。

src/supervisor/spawner.ts

@@ -1,11 +1,9 @@
 /**
  * Backend abstraction for per-user DSH lifecycle (docs/k8s.md §5.2).
  *
- * `local` spawns child processes (setuid/iptables) via `LocalSpawner`; `k8s`
- * creates/deletes per-user DSH Pods via the K8s API (`K8sSpawner`). The route
- * layer depends only on this interface, so both backends coexist behind the
- * same API. Shared instance/status types live here so neither backend owns
- * them.
+ * `LocalSpawner` spawns child processes (setuid/iptables). The route layer
+ * depends only on this interface. Shared instance/status types live here so
+ * no backend owns them.
  * @module dshs/supervisor/spawner
  */
 
@@ -95,13 +93,11 @@ export interface LivePod {
 /**
  * The lifecycle seam the route layer delegates to.
  *
- * `endpointFor` is spawner-specific: local → `127.0.0.1:<port>`, k8s → the
- * per-user Headless Service DNS (docs/k8s.md §5.4).
+ * `endpointFor` is spawner-specific: `127.0.0.1:<port>` for the local backend
+ * (docs/k8s.md §5.4).
  *
- * `launch` takes the rendered cordis patch as **content**, not a path: under
- * k8s the control plane holds no user volume, so it can neither write the patch
- * nor read it back. `LocalSpawner` materializes it to a file (it does have the
- * volume) and `K8sSpawner` puts it straight into a ConfigMap.
+ * `launch` takes the rendered cordis patch as **content**, not a path;
+ * `LocalSpawner` materializes it to a file inside the user's own volume.
  */
 export interface Spawner {
   launch(userId: string, folder: string, patch?: string, opts?: { force?: boolean }): Promise<Instance>