Add instance nav prefs, env config UI, and PM2 restart.

P1-P4: configurable nav/section visibility in system settings, full .env editor with restart badges, password change, runtime hot overrides, and single-instance pm2 restart. Works in hub embed iframe.
Co-authored-by: Cursor <cursoragent@cursor.com>

lib/instance/instance_settings_lib.py

@@ -184,6 +184,7 @@ def build_instance_settings_view(
 
 
 def settings_page_context(page: str, **kwargs: Any) -> dict[str, Any]:
-    if (page or "").strip() not in ("settings", "risk_policy"):
+    p = (page or "").strip()
+    if p not in ("settings", "risk_policy", "env_config"):
         return {}
     return {"instance_settings": build_instance_settings_view(**kwargs)}