Discover movies & tv shows by genre (#1610)

## Description
Adds genre rows for movies & TV shows to the discover page. These work
the same as on the Seerr web UI, clicking one will show media in the
genre.

### Related issues
Related to https://github.com/damontecres/Wholphin/issues/702

### Testing
Just on the emulator so far

## Screenshots
<img width="1280" height="720" alt="discover_genres Large"
src="https://github.com/user-attachments/assets/93e5ef25-e253-49bc-9009-89f814889c98"
/>


## AI or LLM usage
None

app/src/main/java/com/github/damontecres/wholphin/services/SeerrService.kt

@@ -161,10 +161,12 @@ class SeerrService
                 null
             }
 
-        private suspend fun createImageUrl(
+        suspend fun createImageUrl(
             imageType: ImageType,
             path: String?,
             mediaInfo: MediaInfo?,
+            backdropHeight: Int = 1080,
+            backdropWidth: Int = 1920,
         ): String? {
             if (mediaInfo != null) {
                 val itemId =
@@ -193,7 +195,7 @@ class SeerrService
             val prefix =
                 when (imageType) {
                     ImageType.PRIMARY -> "/t/p/w500"
-                    ImageType.BACKDROP -> "/t/p/w1920_and_h1080_multi_faces"
+                    ImageType.BACKDROP -> "/t/p/w${backdropWidth}_and_h${backdropHeight}_multi_faces"
                     else -> throw IllegalArgumentException("Image type not supported: $imageType")
                 }
             return "${base}${prefix}$path"