Merge branch 'initial-ui' into 'main'

.idea/codeStyles/Project.xml

build.gradle

gradle/ktlint.gradle

mailbox-android/build.gradle

mailbox-android/src/main/AndroidManifest.xml

...riarproject/mailbox/android/MailboxNotificationManager.kt

...java/org/briarproject/mailbox/android/MailboxViewModel.kt

...ain/java/org/briarproject/mailbox/android/MainActivity.kt

...org/briarproject/mailbox/android/ui/OnboardingActivity.kt

...org/briarproject/mailbox/android/ui/OnboardingFragment.kt

...rg/briarproject/mailbox/android/ui/OnboardingViewModel.kt

...riarproject/mailbox/core/system/AndroidTaskScheduler.java

mailbox-android/src/main/res/drawable/ic_circle.xml

...-android/src/main/res/layout-land/fragment_onboarding.xml

mailbox-android/src/main/res/layout/activity_main.xml

mailbox-android/src/main/res/layout/activity_onboarding.xml

mailbox-android/src/main/res/layout/fragment_onboarding.xml

mailbox-android/src/main/res/navigation/nav_main.xml

mailbox-android/src/main/res/values-night/themes.xml

mailbox-android/src/main/res/values/colors.xml