improve Gemini transcription prompt for consistent JSON output
Remove markdown code block and ellipsis from output format spec, replace
with inline JSON example and explicit "do not wrap in an array" constraint.
Gemini was intermittently returning non-standard shapes ([{"segments": [...]}],
bare arrays) — clearer instructions produce consistent {"segments": [...]}
responses.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>