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/run/__tests__/RunSetup.test.tsx

@@ -4,7 +4,7 @@
  * `PromptEditor`'s `/` and `@` autocomplete (Enter picks while the list is
  * open, `/` only where slash commands apply), Shift/Alt+Enter newlines, a
  * pasted image shown as a thumbnail and sent as its saved path, and `ModelPicker` — a tool's own
- * list from the server, a fixed list (an AI Router's models) when given one,
+ * list from the server, a fixed list (an AI Proxy's models) when given one,
  * and Custom…, which is a sentinel, never a model id — and `ModelMenu`, the
  * same list as one chip: aliases up front, pinned versions under More models,
  * plus the effort slider.
@@ -211,7 +211,7 @@ describe("ModelPicker", () => {
     expect(await screen.findByText("GPT-6-Sol")).toBeTruthy();
   });
 
-  it("offers only a fixed list when given one (an AI Router's models)", async () => {
+  it("offers only a fixed list when given one (an AI Proxy's models)", async () => {
     render(
       <ModelPicker
         value=""