implement Hilt, DataStore, and Jellyfin SDK

- Setup Hilt for dependency injection and KSP for annotation processing.
- Add DataStore for user session management with JSON serialization.
- Integrate Jellyfin SDK and create a basic `JellyfinApiClient`.
- Replace `MainActivity` with `PurefinActivity` featuring a login flow and a placeholder home screen.
- Implement custom UI components: `PurefinComplexTextField`, `PurefinPasswordField`, and `PurefinTextButton`.
- Update version catalog with new dependencies and downgrade SDK versions to 35.

build.gradle.kts

@@ -1,5 +1,8 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 plugins {
     alias(libs.plugins.android.application) apply false
+    alias(libs.plugins.kotlin.android) apply false
     alias(libs.plugins.kotlin.compose) apply false
+    alias(libs.plugins.ksp) apply false
+    alias(libs.plugins.hilt) apply false
 }