Honor keepLoaded for services during plugin hot-reload (#9485)

* Honor keepLoaded for services during plugin hot-reload

Plugin reload destroyed every service, including omarchy.lock, which drops the ext-session-lock client while Hyprland still holds the lock and surfaces the crashed-lockscreen fallback.

* Prove keepLoaded service survival with a fixture service

A fresh lock service also reports an empty lastEventAt, so comparing it
across the rescan passed whether or not the instance survived. A fixture
keepLoaded service whose in-memory marker is set before the rescan and
read back after can only pass when the same instance is still mounted.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Drop kept services whose plugin no longer declares a service

The _syncServices cleanup only asked whether the plugin was still
installed and enabled, so a kept service whose plugin dropped its
service kind or entry point kept running as a zombie until shell
restart. Apply the same eligibility checks used at creation, and hand
kept instances the refreshed manifest after a rescan.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Cover omarchy.media in keepLoaded expectations; note kept services reload on restart

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: David Heinemeier Hansson <david@hey.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

shell/plugins/README.md

@@ -83,6 +83,9 @@ separate PAM services: `omarchy-lock-password` for password auth and,
 only when fingerprints are enrolled, `omarchy-lock-fingerprint` for
 fingerprint auth. It mirrors the previous lock screen field dimensions,
 colors, blurred wallpaper, placeholder, and Hyprland-driven corners.
+The plugin sets `keepLoaded: true` so a plugin hot-reload (for example
+an installed bar widget changing on disk) does not destroy the lock
+client while Hyprland still holds the session lock.
 
 ## Polkit agent