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.

app/src/main/AndroidManifest.xml

@@ -1,8 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:tools="http://schemas.android.com/tools">
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
 
     <application
+        android:name=".PurefinApplication"
         android:allowBackup="true"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:fullBackupContent="@xml/backup_rules"
@@ -12,7 +12,7 @@
         android:supportsRtl="true"
         android:theme="@style/Theme.Purefin">
         <activity
-            android:name=".MainActivity"
+            android:name=".PurefinActivity"
             android:exported="true"
             android:label="@string/app_name"
             android:theme="@style/Theme.Purefin">