[model-gateway]: move unit tests to bindings/python/tests/ (#16430)

sgl-model-gateway/bindings/python/README.md

@@ -6,16 +6,22 @@ This directory contains the Python bindings for the SGLang Router, built using [
 
 ```
 bindings/python/
-├── src/                    # Rust source code for Python bindings
-│   └── lib.rs              # PyO3 bindings implementation
-├── sglang_router/          # Python source code
-│   ├── __init__.py
-│   ├── version.py
-│   ├── launch_server.py
-│   ├── launch_router.py
-│   ├── router.py
-│   ├── router_args.py
-│   └── mini_lb.py
+├── src/                    # Source code (src layout)
+│   ├── lib.rs              # Rust/PyO3 bindings implementation
+│   └── sglang_router/      # Python source code
+│       ├── __init__.py
+│       ├── version.py
+│       ├── launch_server.py
+│       ├── launch_router.py
+│       ├── router.py
+│       ├── router_args.py
+│       └── mini_lb.py
+├── tests/                  # Python unit tests
+│   ├── conftest.py
+│   ├── test_validation.py
+│   ├── test_arg_parser.py
+│   ├── test_router_config.py
+│   └── test_startup_sequence.py
 ├── Cargo.toml              # Rust package configuration for bindings
 ├── pyproject.toml          # Python package configuration
 ├── setup.py                # Setup configuration
@@ -51,15 +57,15 @@ pip install dist/sglang_router-*.whl
 ## Testing
 
 ```bash
-# Run Python tests
-cd sgl-model-gateway
-pytest py_test/
+# Run Python unit tests (after maturin develop)
+cd sgl-model-gateway/bindings/python
+pytest tests/
 ```
 
 ## Configuration
 
 - **pyproject.toml**: Defines package metadata, dependencies, and build configuration
-- **python-source**: Set to "." to indicate Python source is in the same directory as pyproject.toml
+- **python-source**: Set to `"src"` indicating Python source uses the src layout
 - **module-name**: `sglang_router.sglang_router_rs` - the Rust extension module name
 
 ## Notes