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

server/routes/settings.js

@@ -461,7 +461,7 @@ function homeRoutes(route, key, field, get, set) {
 
 // GET/PUT /api/settings/claude-home
 homeRoutes("/claude-home", "CLAUDE_HOME", "claude_home", getClaudeHome, setClaudeHome);
-// GET/PUT /api/settings/codex-home — a session's AI Router layer is written
+// GET/PUT /api/settings/codex-home — a session's AI Proxy layer is written
 // into the current home at its spawn, so a move needs no repair here.
 homeRoutes("/codex-home", "CODEX_HOME", "codex_home", getCodexHome, setCodexHome);