fix(plugin): restart a server left on a retired plugin root

A plugin update applied mid-session (/plugin followed by /reload-plugins)
fires no SessionStart, so the bootstrap's version handover never runs and the
dashboard server keeps executing a cache directory Claude Code has already
discarded. /ccam-open then rebuilt the bundle from the new root against that
old server, and the new bundle called routes the old server never had:
/api/lanes/pipeline-stats fell through to /:id and rendered "lane not found",
/api/workflows/skill-usage fell through to the SPA catch-all and broke
JSON.parse on the returned HTML. Both Workflows panels showed an error while
the code they needed was sitting on disk.

plugin-open now re-runs bootstrap when the live server's recorded pluginRoot
differs from the current one, or when no server is live at all. Bootstrap
already owns the stop/start and the dependency install the new root may need,
so this only restores the trigger that a mid-session update skips.

scripts/plugin-open.js

@@ -6,7 +6,10 @@
  * on session start, so client-only routes (e.g. `/run`) work the moment
  * `claude` is started, not just the API and MCP tools. `/ccam-open` re-runs
  * this standalone — a no-op when the bundle already matches — as a fallback
- * for `--force` rebuilds or a first build that failed during bootstrap.
+ * for `--force` rebuilds or a first build that failed during bootstrap, and it
+ * re-runs bootstrap first when the live server belongs to a retired plugin root
+ * (a mid-session `/plugin` update) so the new bundle is not left calling routes
+ * the running server never had.
  *
  * The client source is copied out of the (replaced-on-update) plugin cache into
  * the runtime dir before building, so neither the cache nor the checkout is
@@ -74,12 +77,21 @@ function dashboardUrl() {
 }
 
 if (require.main === module) {
+  // A plugin update applied mid-session (/plugin + /reload-plugins) fires no
+  // SessionStart, so the server keeps executing a cache dir Claude Code has
+  // already retired: a bundle rebuilt from the new root then calls routes that
+  // old server never had. Hand the version handover back to bootstrap, which
+  // owns stop/start and the dependency install the new root may need.
+  const stale = (boot.readState() || {}).pluginRoot !== PLUGIN_ROOT || !boot.serverIsLive();
+  if (stale) boot.bootstrap();
+
   const result = buildClient({ force: process.argv.includes("--force") });
   if (result === "failed") {
     console.error("Client build failed — the API and MCP tools still work.");
     process.exitCode = 1;
   } else {
     if (result === "built") console.log("Dashboard UI built.");
+    if (stale) console.log("Server restarted on the current plugin version.");
     console.log(dashboardUrl());
   }
 }