feat(Calendar): update localization and enhance regression checklist

- Updated the regression checklist to reflect the completion of Phase 14.
- Incremented versionCode to 4 and versionName to 1.2.0 in build.gradle.kts for the new release.
- Added new localization keys for calendar features in multiple languages, improving user accessibility and clarity.
- Enhanced the generate-mobile-i18n script to support new calendar translations, ensuring comprehensive coverage across locales.

mobile-app/composeApp/build.gradle.kts

@@ -58,8 +58,8 @@ android {
         applicationId = "de.tsschulz.tt_tagebuch"
         minSdk = libs.versions.android.minSdk.get().toInt()
         targetSdk = libs.versions.android.targetSdk.get().toInt()
-        versionCode = 3
-        versionName = "1.1.0"
+        versionCode = 4
+        versionName = "1.2.0"
         buildConfigField("String", "BACKEND_BASE_URL", "\"$backendBaseUrl\"")
         buildConfigField("String", "SOCKET_BASE_URL", "\"$socketBaseUrl\"")
     }