fix(settings): keep the relock timeout behind the PIN and bind M3U group lock toggles to their playlist

A locked session can no longer change the relock timeout: the Settings
selector is disabled until the PIN is entered and the service refuses
the change while locked. An M3U right-click lock toggle now captures its
playlist before the PIN prompt and is saved only if that playlist is
still open.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/web/src/app/settings/settings-parental-section.component.html

@@ -82,7 +82,7 @@
                     <mat-select
                         data-test-id="parental-lock-relock"
                         [value]="relockMinutes()"
-                        [disabled]="busy()"
+                        [disabled]="busy() || !unlocked()"
                         (selectionChange)="
                             relockMinutesChanged.emit($event.value)
                         "