refactor: consolidate to handler-base, migrate to pyproject.toml, add tests

pyproject.toml

@@ -0,0 +1,40 @@
+[project]
+name = "chat-handler"
+version = "1.0.0"
+description = "Text chat pipeline with RAG - Query → Embeddings → Milvus → Rerank → LLM"
+readme = "README.md"
+requires-python = ">=3.11"
+license = { text = "MIT" }
+authors = [{ name = "Davies Tech Labs" }]
+
+dependencies = [
+    "handler-base @ git+https://git.daviestechlabs.io/daviestechlabs/handler-base.git",
+]
+
+[project.optional-dependencies]
+dev = [
+    "pytest>=8.0.0",
+    "pytest-asyncio>=0.23.0",
+    "ruff>=0.1.0",
+]
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+packages = ["."]
+only-include = ["chat_handler.py"]
+
+[tool.ruff]
+line-length = 100
+target-version = "py311"
+
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+testpaths = ["tests"]
+python_files = ["test_*.py"]
+python_classes = ["Test*"]
+python_functions = ["test_*"]
+addopts = "-v --tb=short"
+filterwarnings = ["ignore::DeprecationWarning"]