implement Media3 ExoPlayer for video playback

- Add Media3 UI, ExoPlayer, and Compose dependencies.
- Implement `PlayerActivity` with landscape orientation for video playback.
- Create `PlayerViewModel` to manage ExoPlayer lifecycle and media loading via Hilt.
- Define `VideoPlayerModule` to provide a configured `ExoPlayer` instance with tunneling and custom load control.
- Extend `JellyfinApiClient` to fetch media sources and video stream URLs.
- Update `ContinueWatchingCard` to launch `PlayerActivity` when the play button is clicked.
- Enforce portrait orientation for the main application and filter duplicate items in `HomePageViewModel`.

app/src/main/AndroidManifest.xml

@@ -4,6 +4,7 @@
     <application
         android:name=".PurefinApplication"
         android:allowBackup="true"
+        android:screenOrientation="portrait"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:fullBackupContent="@xml/backup_rules"
         android:icon="@mipmap/ic_launcher"
@@ -22,6 +23,11 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+        <activity
+            android:name=".player.PlayerActivity"
+            android:screenOrientation="landscape"
+            android:exported="false"
+            android:theme="@style/Theme.Purefin" />
     </application>
 
-</manifest>
+</manifest>