feat: v2.5.5 — AI Router renamed AI Proxy, reload onto new builds, update no longer spins

AI Proxy (was AI Router):
- server/lib/ai-proxies.js, proxy-apply.js, routes/ai-proxies.js mounted at
  /api/ai-proxies and the old /api/ai-routers; `router` still accepted on the
  start routes; profiles move to <CLAUDE_HOME>/agenthub-proxies/
- dashboard_runs.router renamed in place to proxy: an older build on the same
  DB fails on that column, so dev and prod sharing one DB update together
- a proxy's baseUrl stored as its root (a typed /v1 made /v1/v1/messages);
  Test probes Claude /v1/messages and Codex /v1/responses
- Settings → AI Proxy (/settings/ai-router redirects), ProxyPicker

Updates:
- every tab reloads onto the new UI build when its WebSocket reconnects to a
  server of another version (lib/newBuildReload.ts, once per version)
- Update now stops waiting on a plugin chain that failed or pulled nothing
  (the old server never goes down), and reloads as soon as a new version answers

Also:
- a pane whose command exits at once says so (EPANEEXITED) instead of
  "Command failed: tmux set-option … mouse on"
- the pane drag preview draws where the pane actually lands

client/src/components/UpdateNotifier.tsx

@@ -85,6 +85,7 @@ import { Download, X, Copy, Check, RefreshCw, Zap, ExternalLink } from "lucide-r
 import { api } from "../lib/api";
 import { eventBus } from "../lib/eventBus";
 import { copyText } from "../lib/clipboard";
+import { toast } from "../lib/toast";
 import { useDialog } from "../hooks/useDialog";
 import type { UpdateStatusPayload, WSMessage } from "../lib/types";
 
@@ -264,22 +265,41 @@ export function UpdateNotifier() {
    *   stretch, so polling naively would get a 200 from the process we are
    *   waiting to replace and reload onto the same old bundle.
    */
-  const pollUntilBack = useCallback((requireDownFirst = false) => {
-    let sawDown = !requireDownFirst;
-    const attempt = () => {
-      api.updates
-        .status()
-        .then(() => {
-          if (sawDown) window.location.reload();
-          else setTimeout(attempt, 1500);
-        })
-        .catch(() => {
-          sawDown = true;
-          setTimeout(attempt, 1500);
-        });
-    };
-    setTimeout(attempt, 1500);
-  }, []);
+  const pollUntilBack = useCallback(
+    (requireDownFirst = false, fromVersion: string | null = null) => {
+      let sawDown = !requireDownFirst;
+      // Its own verdicts only: an older plugin-update.json is still on disk
+      // until this chain writes one (5 s slack for a clock a little behind).
+      const since = Date.now() - 5000;
+      const attempt = () => {
+        api.updates
+          .status()
+          .then((s) => {
+            const v = s.last_plugin_update;
+            const mine = !!v?.finished_at && Date.parse(v.finished_at) >= since;
+            // A failed step, or nothing to pull, leaves the OLD server up: it
+            // never goes down, so waiting for that spun "Restarting…" forever.
+            if (requireDownFirst && v && mine && (v.ok === false || v.step === "already_current")) {
+              syncFromPayload(s);
+              setRestarting(false);
+              if (v.ok) toast.info(t("pluginAlreadyCurrent"));
+              return;
+            }
+            // A new version answering is back too, even if a poll never
+            // landed in the short gap between the old server and the new one.
+            const moved = !!fromVersion && !!s.local_version && s.local_version !== fromVersion;
+            if (sawDown || moved) window.location.reload();
+            else setTimeout(attempt, 1500);
+          })
+          .catch(() => {
+            sawDown = true;
+            setTimeout(attempt, 1500);
+          });
+      };
+      setTimeout(attempt, 1500);
+    },
+    [syncFromPayload, t]
+  );
 
   const applyNow = async () => {
     if (applying || restarting) return;
@@ -292,7 +312,7 @@ export function UpdateNotifier() {
         setRestarting(true);
         // mode "plugin": the old server lingers while the chain installs, so
         // only treat a reachable server as "back" after it has gone away once.
-        pollUntilBack(result.mode === "plugin");
+        pollUntilBack(result.mode === "plugin", status?.local_version ?? null);
         return;
       }
       setError(