feat(ai-proxy): Update 9router button — shut down, npm update, relaunch hidden

Settings → AI Proxy gains an admin-only Update 9router button beside
Config 9router. One in-memory job (server/lib/nine-router-update.js) stops
9router (its user unit, else this account's own 9router processes), runs
npm install -g --prefix <its prefix> 9router@latest (sudo -n only when
sudoers already allows it, probed before anything stops), then relaunches
it hidden only if it was running. A failed update still relaunches the old
version. Nothing in the request names a command, path or package.

client/src/lib/api.ts

@@ -3281,6 +3281,12 @@ export const api = {
     list: () => request<{ items: AiProxy[] }>("/ai-proxies"),
     /** GET /api/ai-proxies/9router - whether a `9router` binary is installed on the server. */
     nineRouter: () => request<{ installed: boolean }>("/ai-proxies/9router"),
+    /** GET /api/ai-proxies/9router/update - versions, whether it runs, why an update would be refused, the job. */
+    nineRouterUpdateStatus: (fresh = false) =>
+      request<NineRouterUpdateStatus>(`/ai-proxies/9router/update${fresh ? "?fresh=1" : ""}`),
+    /** POST /api/ai-proxies/9router/update - shut 9router down, update it, start it again hidden (admin). */
+    nineRouterUpdate: () =>
+      request<NineRouterUpdateJob>("/ai-proxies/9router/update", { method: "POST" }),
     /** POST /api/ai-proxies - save a new profile. */
     create: (body: AiProxyInput) =>
       request<AiProxy>("/ai-proxies", { method: "POST", body: JSON.stringify(body) }),
@@ -4836,6 +4842,38 @@ export interface AiProxy {
  *  error is still a successful HTTP call: `ok` is the PROXY's verdict, `status`
  *  is its HTTP code (null when nothing answered at all), and `message` is its
  *  own words — truncated server-side, never the key. */
+/** One step of the 9router update job, in order: shutdown → update → relaunch. */
+export interface NineRouterUpdateStep {
+  id: "shutdown" | "update" | "relaunch";
+  status: "pending" | "running" | "done" | "failed" | "skipped";
+  message: string | null;
+}
+
+/** The server's one 9router update job (in memory; null before the first). */
+export interface NineRouterUpdateJob {
+  status: "running" | "done" | "failed";
+  startedAt: string;
+  finishedAt: string | null;
+  from: string | null;
+  to: string | null;
+  managedBy: "systemd" | "process" | null;
+  install: "direct" | "sudo";
+  steps: NineRouterUpdateStep[];
+  log: string;
+}
+
+/** GET /api/ai-proxies/9router/update. `blocker` is why a start would be refused now. */
+export interface NineRouterUpdateStatus {
+  installed: boolean;
+  version: string | null;
+  latest: string | null;
+  updateAvailable: boolean;
+  running: boolean;
+  managedBy: "systemd" | "process" | null;
+  blocker: { code: string; message: string; command?: string } | null;
+  job: NineRouterUpdateJob | null;
+}
+
 export interface AiProxyProbe {
   ok: boolean;
   status: number | null;