Hide empty transcript tabs

[ComputelessComputer]

Treat transcript rows without words as empty and show related meetings without an empty transcript panel.

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Note

Medium Risk
Changes session bottom-panel visibility and audio vs URL semantics across several UI entry points; behavior is well covered by new tests but affects post-session UX paths.

Overview
Treats “has transcript” as rows with actual words, not merely linked transcript IDs, so empty transcript storage no longer drives the bottom panel.

Splits audio presence from playback readiness: audioExists comes from the audio player query (URL is no longer treated as proof of existence), while playback waits on audioUrlReady and the post-session chrome can stay visible during isAudioLoading.

Bottom accessory behavior hides the Transcript tab when there is nothing to show (no words, no playback, no batch run), defaulting to Related meetings only; batch transcription errors still show the transcript tab/panel so failures remain visible. Expanded tests cover these cases.

^{Reviewed by Cursor Bugbot for commit c18b15b. Bugbot is set up for automated code reviews on this repo. Configure here.}

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This is part 1 of 2 in a stack made with GitButler:

•  2  Reduce bottom accessory render work #5559
•  1  Hide empty transcript tabs #5556 👈

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Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

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