Download audio cache segments sequentially to avoid API rate limits

[enaboapps]

Problem

In OnlineTalkPage.tsx, all missing audio segments are fetched in parallel via Promise.all. For talks with many segments this hammers the TTS API simultaneously, hitting concurrency/rate limits and causing failures.

Solution

Replace the parallel Promise.all fetch with a sequential loop — fetch one segment at a time, update progress after each one.

Changes required

• app/talk/[id]/OnlineTalkPage.tsx — replace Promise.all(misses.map(...)) with a for...of loop