Add zap repeat interval; flash countdown when expired

src/c/settings.h

@@ -12,6 +12,7 @@
 typedef struct AppSettings {
     bool TutorialEnabled;
     bool PavlokEnabled;
+    uint8_t PavlokIntervalSeconds;
     uint8_t AwarenessTimeGapMinutes;
     uint8_t AwarenessTimeLimitSeconds;
     uint8_t AwarenessNudgeEnabled;