Plugin manager waits for pending toggles and clarifies when changes apply

What

• Closing the plugin manager menu after toggling plugins used to show a static reminder message immediately. Now it tracks in-flight enable/disable promises and, if any are still pending, waits for all of them to settle before returning to the menu, instead of firing the reminder text before the toggle finished.
• The reminder text is now conditional on a new changesApplyOnClose flag: when set, plugin-enable confirmations say the change applies as soon as the menu closes; otherwise they still tell you to run /reload-plugins.
• The installed-plugins management screen now receives this changesApplyOnClose prop, wired to the same "needs refresh" state used for the reload prompt.

Why This avoids showing a misleading confirmation before a plugin toggle has actually finished, and makes clear whether you need to run /reload-plugins or the change already took effect.