Evaluate upstream Apollo/BS-Roformer model support (PR #2153)

[dotdevdotdev]

Status: OPEN — not started, feature (not a compat fix)

Context

Upstream Anjok07#2153 adds Apollo and BS-Roformer/Mel-Band-Roformer model support — new separation architectures, a real feature request. Set aside during the compat-fixing triage (#1/#2/#3/#4) because it's additive scope, not a bug/install fix, and is a large diff.

Scope

~3600 insertions upstream: new lib_v5/apollo_inference.py, lib_v5/apollo_model_data/, lib_v5/attend.py, lib_v5/bs_roformer.py, lib_v5/mel_band_roformer.py, plus changes to separate.py and requirements.txt (adds requirements-stable.txt).

Remaining

• Decide priority relative to the other open work (deps/GPU/CLI/Windows verification).
• If pursued, needs its own testing pass similar to how Add Apple Silicon MPS inference backend + fix librosa API breaks (tested on real M4 hardware) #8 (MPS backend) was validated with tools/smoke_inference.py — new model architectures are exactly the kind of change that needs real inference testing, not just import testing (see the librosa lesson from Modernize pinned dependencies (root cause of most Linux install failures) #1/macOS compatibility issues (older macOS versions, MPS backend) #4).

Evidence / links

Upstream PR: Anjok07#2153