release: cut v1.4.0 — reminder notifications

Version bumped to 1.4.0 / 12. No code changes beyond the version — 1.4.0 is
the reviewed-and-approved reminder slice: the EVENT_REMINDER receiver posting
due CalendarAlerts on a dedicated channel, tap-to-detail, the one-time
onboarding step requesting POST_NOTIFICATIONS with the duplicate-reminders
warning, and the Settings mirror. CHANGELOG [1.4.0] carries the details.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/build.gradle.kts

@@ -23,8 +23,8 @@ android {
         applicationId = "de.jeanlucmakiola.calendula"
         minSdk = 29
         targetSdk = 36
-        versionCode = 11
-        versionName = "1.3.0"
+        versionCode = 12
+        versionName = "1.4.0"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }