Create src/lib/server/data-dir.ts as single source of truth for DATA_DIR
using db.ts's $HOME-based convention. All four modules now import from it
instead of defining their own inline default (some resolving to /tmp/.whisper-pwa).
Changes:
- src/lib/server/data-dir.ts — new file, exports DATA_DIR const
- db.ts — import DATA_DIR from data-dir.ts (same logic, same path)
- audio.ts — import DATA_DIR, replace inline process.env.DATA_DIR ?? '/tmp/...'
- downloader.ts — import DATA_DIR, replace inline '/tmp/.whisper-pwa'
- remux.ts — import DATA_DIR, replace inline process.env.DATA_DIR ?? '/tmp/...'
- tests/data-dir.test.ts — 10 tests covering default, custom, and module integrity
- tests/retry-pipeline.test.ts — fix stale hardcoded /tmp/.whisper-pwa/uploads
path; compute parent dir from getUploadPath() dynamically
Test pass rate: 217/220 (3 pre-existing failures unrelated to DATA_DIR)
- 2 D5 downloader tests need yt-dlp (not available in test env)
- All other tests green, including the new data-dir.test.ts (10/10)
