refactor(file_transcriber): extract methods from FileTranscriber.run to fix R0915

[josiasdev]

Why is this change needed?

The FileTranscriber.run method had 58 statements, exceeding Pylint's limit of 50 (too-many-statements / R0915). This made the method overly long and difficult to read, test, and maintain. It mixed three distinct responsibilities:

1. URL downloading (yt-dlp extraction + ffmpeg conversion)
2. Transcription orchestration (calling transcribe, stripping segments, emitting signals, writing output files)
3. Folder watch file handling (removing or moving the source file post-transcription)

How was it tested?

• Ran all transcriber tests with uv run pytest tests/transcriber/ -v
• All tests passed except one pre-existing unrelated failure (test_missing_file in whisper_file_transcriber_test — a UnicodeDecodeError in the av library)
• Pylint R0915 check now passes: Your code has been rated at 10.00/10

What was changed?

Two private helper methods were extracted from run:

• _download_from_url(self) -> bool — encapsulates the entire URL import flow: video title extraction, yt-dlp download, ffmpeg conversion to WAV, and Windows-specific subprocess handling. Returns False on download failure so run can abort early.
• _handle_folder_watch(self) — encapsulates the FOLDER_WATCH source file management (remove or move).

The run method was simplified from ~58 statements to ~20, now acting as a clear orchestrator of these steps.

Notes for the reviewer

• The _download_from_url method returns a bool instead of raising an exception on download failure. This is intentional: the original code used a bare return to exit run early when the download failed, and a boolean return preserves that control flow cleanly without introducing exception-based control flow.
• No logic was altered — only extracted. The behavior is identical to the original.

[codecov]

Codecov Report

❌ Patch coverage is 74.65753% with 37 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.88%. Comparing base (b756a47) to head (572ae6e).

Files with missing lines	Patch %	Lines
buzz/transcriber/recording_transcriber.py	74.00%	26 Missing ⚠️
buzz/transcriber/file_transcriber.py	76.08%	11 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1539      +/-   ##
==========================================
+ Coverage   82.85%   82.88%   +0.02%     
==========================================
  Files         108      108              
  Lines       11627    11653      +26     
==========================================
+ Hits         9634     9659      +25     
- Misses       1993     1994       +1     

Flag	Coverage Δ
Linux	81.63% <74.65%> (+0.02%)	⬆️
macOS	82.39% <74.65%> (+0.03%)	⬆️

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