fix(transcribe): default output to project directory

[miguel-heygen]

Summary

• make transcribe honor its documented current-directory default
• keep explicit --dir behavior unchanged
• preserve input-adjacent defaults for --to srt|vtt exports
• avoid writing transcript.json into assets/audio when input media lives there

Source feedback: https://heygen.slack.com/archives/C0BGC335AQY/p1783984033363839

Tests

• bun run --filter @hyperframes/cli test -- src/commands/transcribe.test.ts
• bunx oxfmt --check packages/cli/src/commands/transcribe.ts packages/cli/src/commands/transcribe.test.ts
• bunx oxlint packages/cli/src/commands/transcribe.ts packages/cli/src/commands/transcribe.test.ts
• bun run --filter @hyperframes/cli typecheck

[miguel-heygen]

Closing in the backlog value sweep. This is documentation, test-only, dependency upkeep, refactoring, or narrow diagnostic/ergonomic polish without enough current user impact or an active merge path to justify carrying it open. Please reopen or resubmit against current main if the need is still concrete.

[WaterrrForever]

Flagging before this drops off the radar: this one is a real user-facing defect, not polish — transcribe violates its own documented default and writes transcript.json into assets/audio, and it came from a reproduction-backed feedback report. None of the open consolidation PRs (#2403/#2410/#2413) touch the transcribe path, so closing here drops the fix entirely and the same report will keep coming back through the digest. Can we either fold it into one of the consolidations or reopen this? The diff is +17/-5 with tests.