Release 1.2.1

- Fixed the dictionary update card taking too long to reappear after
  cancelling a download (DownloadManager).
- Bump agp 9.3.0 -> 9.3.1; migrate the release build type from
  isMinifyEnabled/isShrinkResources/proguardFiles to
  optimization { enable = true } with keep rules moved to
  app/src/release/keepRules/proguard-rules.keep.

gradle/libs.versions.toml

@@ -1,7 +1,7 @@
 [versions]
 aboutlibraries = "15.0.4"
 activity_compose = "1.13.0"
-agp = "9.3.0"
+agp = "9.3.1"
 compose_bom = "2026.06.01"
 core = "1.19.0"
 datastore_preferences = "1.2.1"