Kiosk: apply schedule engine in playback and add System Settings toggle

ScrollerPage now resolves the active Block from ScheduleManager (reusing
the existing stream-switch path), honoring dynamicAudio true/false and
falling back to local selection for gaps, no schedule, or toggle off.
Adds a 'Schedule' On/Off entry (default On) in System Settings persisted
in config.yaml, and config plumbing (proclamation.schedule_enabled). All
on-device schedule times remain 12h AM/PM.

src/app_state.h

@@ -8,6 +8,7 @@
 #include "network/network_manager.h"
 #include "network/license_status.h"
 #include "network/system_name_sync.h"
+#include "schedule/schedule_manager.h"
 #include "audio/audio_manager.h"
 #include "audio/audio_downloader.h"
 
@@ -21,6 +22,7 @@ struct AppState {
     radiantwave::network::NetworkManager network;
     radiantwave::license::LicenseStatusTracker licenseTracker;
     radiantwave::systemname::SystemNameSync systemNameSync;
+    radiantwave::schedule::ScheduleManager scheduleManager;
     radiantwave::audio::AudioManager audio;
     radiantwave::audio::AudioDownloader audioDownloader;
     bool quitRequested = false;