Alarm handled using background task.

The alarm for deadlines is now handled via a background task. Instead of a scheduled task that prevents sleep mode, the face checks in the background every minute whether an deadline is due. If this is the case, the face wakes up from sleep mode and starts a scheduled task for the remaining seconds.

movement/watch_faces/complication/deadline_face.h

@@ -44,6 +44,7 @@ typedef struct {
     uint8_t current_index:2;
     uint8_t alarm_enabled:1;
     uint8_t tick_freq;
+    uint8_t face_idx;
     uint32_t deadlines[DEADLINE_FACE_DATES];
 } deadline_state_t;
 
@@ -51,13 +52,14 @@ void deadline_face_setup(movement_settings_t *settings, uint8_t watch_face_index
 void deadline_face_activate(movement_settings_t *settings, void *context);
 bool deadline_face_loop(movement_event_t event, movement_settings_t *settings, void *context);
 void deadline_face_resign(movement_settings_t *settings, void *context);
+bool deadline_face_wants_background_task(movement_settings_t *settings, void *context);
 
 #define deadline_face ((const watch_face_t){ \
     deadline_face_setup, \
     deadline_face_activate, \
     deadline_face_loop, \
     deadline_face_resign, \
-    NULL, \
+    deadline_face_wants_background_task \
 })
 
 #endif                          // DEADLINE_FACE_H_