Generative Transcripts not available

### Description

I have tried multiple different podcasts, but for each the "transcript" button is grayed out. The tooltip upon pressing it says "Sorry, but this episode has no transcript available". Since most of my episodes I downloaded, I thought that might be the problem, but it also happens with streaming episodes.

Any help is appreciated.

-- Jakob

### Step-by-step reproduction instructions

1. Play any podcast episode
2. Switch to "Now Playing" view
3. Try to press transcript button.

### Screenshots or screen recording



### Did you search for existing bug reports?

- [x] I have searched for existing bug reports.

### Device, Operating system, and Pocket Casts app version

* Account type: Pocket Casts Champion
* Device: Pixel 7
* OS: Android 15
* App version: 7.88-rc-1

Start by reproducing the issue from the Now Playing view using the listed steps on Android 15 with app version 7.88-rc-1. Trace how the transcript button determines availability for both downloaded and streaming podcast episodes; done means the expected episodes expose a working transcript or the availability behavior is corrected.

Written by the indexing model from the issue text.