By: Michael Lynch <git@mtlynch.io>
Let WriteConverted produce temp files directly Remove WriteConverted's source reader argument so callers provide a producer callback that writes converted content to the temporary file. This lets call sites control how they read source media while preserving the temp-file buffering before MediaWriter writes.
| Time to Start | Worker time | Duration | Time to finish | |
| Config | 2s | 11s | 11s | 14s |
| Eval | 9s | 2m36s | 2m36s | 2m46s |
| Build | 38s | 8m12s | 12m28s | 13m07s |
| Suite | 2s | 11m01s | 13m04s | 13m07s |