[Bug] [FreshRSS] Adding a category while adding a new feed fails

Checklist

• I've already searched in existing issues and haven't found a similar problem reported.
• I'm using the latest version of the app
• This error caused the app to crash
• This error is reproducible

Which category best fits this error?

Feed Management

App version

0.15.0

Reproduction steps

1. Add a feed

2. Click on + for new Group (category)

3. Add the name

4. Try adding the feed (fails)

5. Add with existing category (succeeds)

6. Go to feed

7. Edit the category

8. Add a new category name (succeeds)

9. Move feed to new category (succeeds)

Crash report

Version: 0.15.0
Device: Google Pixel 10 Pro
System: Android 16 (API 36)

Stack trace: 

(message='BadRequest', query=null, params=null, form=null)
	at me.ash.reader.infrastructure.rss.provider.greader.GoogleReaderAPI$subscriptionEdit$$inlined$retryablePostRequest$default$1.invokeSuspend(GoogleReaderAPI.kt:337)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:9)
	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:115)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:96)
	Suppressed: kotlinx.coroutines.internal.DiagnosticCoroutineContextException: [StandaloneCoroutine{Cancelling}@d85eac3, Dispatchers.Default]

Start with the feed-add flow and GoogleReaderAPI.kt:337, where subscriptionEdit reports the BadRequest. Reproduce the failure by creating a new category during feed addition, compare it with editing a feed into a new category, and verify that the feed can be added with its newly created category without a crash.