#17120: fix: transcribe all Telegram voice messages, not just mention-gated groups

## Summary Extends preflight transcription to work for ALL voice messages, not just group messages with mention requirements. This ensures Telegram voice messages in DMs and other non-mention-gated contexts are transcribed before being processed by the agent. Previously, transcription only ran for group messages where mentions were required (fix #16789). For DMs and non-mention-gated groups, transcription relied on `applyMediaUnderstanding` which may not have been triggered in all cases. ## Changes - Modified `needsPreflightTranscription` condition in `bot-message-context.ts` to run for all voice messages with no user text, not just group messages with mention requirements - Added test for direct message voice transcription ## Testing - All 437 telegram tests pass - Added new test case for DM voice messages to verify transcription is triggered Fixes openclaw/openclaw#17101 <!-- greptile_comment --> <h3>Greptile Summary</h3> Extends preflight audio transcription to all voice messages regardless of chat type or mention settings. Previously, transcription only ran for mention-gated group messages. The change simplifies the condition from `isGroup && requireMention && hasAudio && !hasUserText && mentionRegexes.length > 0` to just `hasAudio && !hasUserText`, ensuring all audio content (voice messages and audio files) without accompanying text gets transcribed upfront. - Simplified preflight transcription logic in `bot-message-context.ts:404` - Added test coverage for DM voice message transcription - Test suite passes (437 telegram tests) - Maintains existing behavior: audio with captions is not transcribed during preflight <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk - The change is a straightforward simplification that removes unnecessary conditions from the preflight transcription check. The logic is sound: transcribe audio when there's no user text, regardless of chat type. Test coverage is comprehensive (437 tests passing + new DM test), and the change follows the existing pattern established in previous fixes (#16789). The simplified condition is easier to understand and maintains backward compatibility. - No files require special attention _{Last reviewed commit: f791bbe} <!-- greptile_other_comments_section --> <!-- /greptile_comment -->