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.

docs/PLUGINS.md

@@ -149,7 +149,7 @@ output goes to `client-build.log` next to it; the server's own output goes to
 |---|---|
 | `/ccam-doctor` | Node version, bootstrap state, runtime deps, server liveness, duplicate hooks, CLI launcher + PATH, MCP build freshness, UI bundle |
 | `/ccam-update` | Pull the latest `ccam` release via `claude plugin marketplace update` + `claude plugin update ccam@<marketplace> -y`, then reinstall dependencies and restart the server (`plugin-bootstrap.js --force`). The plugin pull needs a manual `/reload-plugins` afterward to take effect in the current session — not scriptable from a command. |
-| `/ccam-open` | Build the UI bundle if missing, then print the dashboard URL |
+| `/ccam-open` | Rebuild the UI bundle and print the dashboard URL. Re-runs the bootstrap first when the server is down or still executing a plugin root that a mid-session `/plugin` update retired, so a fresh bundle never talks to an older server's routes |
 
 ### Where things live