release: cut v1.2.0 — event creation

Version bumped to 1.2.0 / 9. No code changes beyond the version — 1.2.0 is
the create slice: event form, "+" FAB on every view, last-used-calendar
preselect, provider-correct all-day storage. CHANGELOG [1.2.0] carries the
details; ROADMAP/STATE mark slice v1.2 shipped.

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 = 8
-        versionName = "1.1.0"
+        versionCode = 9
+        versionName = "1.2.0"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }