fix: update PyTorch mask types and BPE tokenizer serialization

- Replace deprecated torch.uint8 and .byte() with torch.bool in GPT.generate
- Add save/load methods to BPETokenizer for proper merges and vocab_list serialization
- Update dependencies in pyproject.toml

uv.lock

@@ -1393,11 +1393,22 @@ dependencies = [
     { name = "torch" },
 ]
 
+[package.optional-dependencies]
+test = [
+    { name = "pytest" },
+    { name = "pytest-cov" },
+    { name = "pytest-mock" },
+]
+
 [package.metadata]
 requires-dist = [
     { name = "numpy", specifier = ">=1.24.0" },
+    { name = "pytest", marker = "extra == 'test'", specifier = ">=7.0.0" },
+    { name = "pytest-cov", marker = "extra == 'test'", specifier = ">=4.0.0" },
+    { name = "pytest-mock", marker = "extra == 'test'", specifier = ">=3.0.0" },
     { name = "torch", specifier = ">=2.3.0" },
 ]
+provides-extras = ["test"]
 
 [[package]]
 name = "llm-arch-research"
@@ -2500,6 +2511,18 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/ee/49/1377b49de7d0c1ce41292161ea0f721913fa8722c19fb9c1e3aa0367eecb/pytest_cov-7.0.0-py3-none-any.whl", hash = "sha256:3b8e9558b16cc1479da72058bdecf8073661c7f57f7d3c5f22a1c23507f2d861", size = 22424, upload-time = "2025-09-09T10:57:00.695Z" },
 ]
 
+[[package]]
+name = "pytest-mock"
+version = "3.15.1"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "pytest" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/68/14/eb014d26be205d38ad5ad20d9a80f7d201472e08167f0bb4361e251084a9/pytest_mock-3.15.1.tar.gz", hash = "sha256:1849a238f6f396da19762269de72cb1814ab44416fa73a8686deac10b0d87a0f", size = 34036, upload-time = "2025-09-16T16:37:27.081Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/5a/cc/06253936f4a7fa2e0f48dfe6d851d9c56df896a9ab09ac019d70b760619c/pytest_mock-3.15.1-py3-none-any.whl", hash = "sha256:0a25e2eb88fe5168d535041d09a4529a188176ae608a6d249ee65abc0949630d", size = 10095, upload-time = "2025-09-16T16:37:25.734Z" },
+]
+
 [[package]]
 name = "python-dateutil"
 version = "2.9.0.post0"