feat(m1): scaffold tsmm package (T1.1)

- pyproject.toml (src-layout, deps per plan)
- src/tsmm/{data,model,train,eval} skeletons
- tests/test_smoke.py (RED->GREEN: importable + subpackages)
- configs/, scripts/, data/, checkpoints/ + .gitignore
- project venv (.venv) for reproducible env (M1 deps only; CUDA torch @ M2)

Verifications: import tsmm OK; pytest tests/ 3 passed.

tests/test_smoke.py

@@ -0,0 +1,25 @@
+"""Smoke tests for the package boundary (T1.1).
+
+These guard the most basic contract: the package is importable and exposes
+a version. If these fail, the install / src-layout is broken.
+"""
+
+import tsmm
+
+
+def test_package_is_importable():
+    assert tsmm is not None
+
+
+def test_package_exposes_version():
+    assert isinstance(tsmm.__version__, str)
+    assert tsmm.__version__  # non-empty
+
+
+def test_subpackages_importable():
+    # M1 will populate these; the skeleton must already expose the namespaces.
+    import importlib
+
+    for sub in ("data", "model", "train", "eval"):
+        mod = importlib.import_module(f"tsmm.{sub}")
+        assert mod is not None