Refactor: Extract FFmpeg utilities into separate module

[stratus-ss]

Extract FFmpeg Utilities into Separate Module

Refactors FFmpeg command construction and execution logic from monkeyplug.py into a dedicated utilities.py module to improve maintainability and testability.

Why?

As I added features in my own fork monkeyplug.py grew fairly large. It also allows for a more easily maintainable code base. In order to support both remote whisper servers as well as file chunking, eventually it allows a separation of concerns moving forward.

Ideally this is the ground work for future feature PRs without overwhelming the monkeyplug.py

Changes

• Extract FFmpegCommandBuilder, AudioFilterBuilder, and FFmpegRunner classes to src/monkeyplug/utilities.py
• Add comprehensive unit tests (test_utilities.py) and functional tests (test_functional.py)
• Add test fixtures and requirements-dev.txt

Benefits

• Easier to test FFmpeg command construction in isolation
• Reduces code duplication
• Maintains backward compatibility
• Improves code organization without changing behavior

Testing

• All existing functionality preserved
• New unit tests cover command builders and runners
• Functional tests validate end-to-end behavior

[selfAndrewKB]

Again, I cannot stress enough how much of a game changer this tool is.

I’ve gone as far as using it to create profanity censor mods for entire video games. The future is bright.