Simplify service lookups with optional chaining

The bar-null-shell-null-typeof-function ternary guarded against our own
shell missing a method it always defines. bar?.shell?.firstPartyServiceFor()
handles the only real case, delayed bar injection, in one line. The
typeof checks that probe genuinely third-party plugin objects stay.

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

shell/plugins/services/media/BarWidget.qml

@@ -7,7 +7,7 @@ BarWidget {
   id: root
   moduleName: "omarchy.media"
 
-  readonly property var mediaService: bar && bar.shell ? bar.shell.firstPartyServiceFor("omarchy.media") : null
+  readonly property var mediaService: bar?.shell?.firstPartyServiceFor("omarchy.media")
   readonly property var activePlayer: mediaService ? mediaService.activePlayer : null
   readonly property var sourcePlayers: mediaService ? mediaService.sourcePlayers : []