Remove setup.py and setup.cfg, fix Docker build

- Remove legacy setup.py and setup.cfg files
- Update pyproject.toml to configure proper package discovery
- Exclude node_modules, tests, examples, and venv from package discovery
- Fix Docker build error caused by multiple top-level packages

Author: sunnywu

pyproject.toml

@@ -5,6 +5,10 @@ requires = [
 ]
 build-backend = "setuptools.build_meta"
 
+[tool.setuptools.packages.find]
+include = ["uid2_client*"]
+exclude = ["tests*", "examples*"]
+
 [project]
 name = "uid2_client"
 version = "2.7.0"