Make musetalk a proper Python package

Add missing __init__.py files so `musetalk.*` subpackages import
without relying on namespace-package behavior or sys.path hacks, and
narrow the root `/models/` gitignore so `musetalk/models/__init__.py`
is tracked.

Also add a minimal pyproject.toml so the source can be installed with
`pip install .` (or `pip install -e .`) without pulling the pinned
requirements.txt, which consumers typically need to override.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pyproject.toml

@@ -0,0 +1,15 @@
+[build-system]
+requires = ["setuptools>=64"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "musetalk"
+version = "1.5.0"
+description = "MuseTalk: audio-driven lip-sync (source-only install; dependencies managed by the consumer)"
+readme = "README.md"
+requires-python = ">=3.10"
+license = { text = "MIT" }
+
+[tool.setuptools.packages.find]
+include = ["musetalk*"]
+exclude = ["scripts*", "assets*", "data*", "configs*"]