refactor: move torch/deepfilternet to optional [full] extra

[MaleicAcid]

Move torch/deepfilternet to optional [full] extra

Motivation

torch, torchaudio, and deepfilternet (~2GB+) are only used in the noise suppression path (noise_suppress=True), which is off by default. Every pip install openlrc currently pulls in these heavy dependencies even though most users only need transcription and translation.

Additionally, torchvision is declared as a dependency but never imported anywhere in the codebase.

Changes

pyproject.toml

• Move torch, torchaudio, and deepfilternet from dependencies to a new [project.optional-dependencies] full extra.
• Remove torchvision entirely (unused).

openlrc/preprocess.py

• Wrap import torch and from df.enhance import ... in noise_suppression() with a try/except ImportError that raises a clear message: "Install them with: pip install openlrc[full]".

openlrc/utils.py

• Make release_memory() gracefully handle missing torch (return early instead of crashing).
• Remove unused import torch from TYPE_CHECKING block.

.github/workflows/ci.yml

• Change uv run python -m unittest to uv run --extra full python -m unittest so CI continues to test the full feature set including noise suppression.

README.md

• Simplify installation steps: remove manual PyTorch, faster-whisper GitHub commit, and typing-extensions install instructions (no longer needed).
• Add step 5 documenting the optional pip install openlrc[full] for noise suppression.
• Update the Lightweight Imports note to reflect that the base install no longer includes torch.
• Annotate the noise_suppress=True code example with (requires openlrc[full]).

Migration

Use case	Install command
Transcription + translation (most users)	pip install openlrc
Transcription + translation + noise suppression	pip install openlrc[full]

Existing users who rely on noise_suppress=True need to change their install command to pip install openlrc[full].

[MaleicAcid]

Hi @zh-plus, this PR is the concrete implementation of the dependency decoupling in #88.

The core change is simple: torch, torchaudio, and deepfilternet move from required dependencies to pip install openlrc[full]. Since noise suppression is off by default, the vast majority of users — those who only need transcription and translation — will never trigger these imports. This cuts ~2GB from the base install, removes the Rust toolchain requirement (deepfilternet), and unblocks torch version upgrades for downstream consumers.

The change is non-breaking for the default install path: all existing code works identically without any modifications. Only users who explicitly pass noise_suppress=True need to add [full] to their install command. The PR also includes an ImportError guard with a clear message pointing them to pip install openlrc[full], so no one will be left confused.

On versioning: since the default install surface changes (fewer packages installed), would you prefer to release this as 1.7.0, or 1.6.3 given that no code behavior changes for the default path?

[zh-plus]

Thanks for the cleanup here. The dependency split looks good overall, and I’m fine merging this PR.

I did notice two small follow-up items:

1. quote the openlrc[full] install command for zsh users
2. realign TranslationConfig type hints with the runtime API/docs (ModelConfig and dict glossary usage)

I’ll handle those separately, so they’re not blocking this PR. Happy to merge.