Fix text import pipeline: raw path, segments.json, format_audio parsing
- Fix raw path depth in imported JSONL metadata (../../ā†'../../../) to
correctly resolve from day/stream/segment/ back to imports/
- Add save_import_segments call for text imports so the import detail
view shows segment info (matching audio import behavior)
- Fix format_audio path parsing to scan for segment key between day dir
and file, supporting both legacy and stream-based layouts
- Stop Callosum connection in importer finally block
- Add PDF import test, format_audio stream/legacy path tests
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>