Drop Python 3.9 support, require >=3.10

Author: johnteee

pyproject.toml

@@ -7,7 +7,7 @@ name = "teaagent"
 version = "0.1.0"
 description = "Governance-first agent harness for autonomous coding tasks."
 readme = "README.md"
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 license = {file = "LICENSE"}
 keywords = ["agent", "governance", "mcp", "audit", "llm"]
 classifiers = [
@@ -16,7 +16,6 @@ classifiers = [
     "License :: OSI Approved :: MIT License",
     "Operating System :: OS Independent",
     "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
@@ -71,7 +70,7 @@ testpaths = ["tests"]
 pythonpath = ["."]
 
 [tool.mypy]
-python_version = "3.9"
+python_version = "3.10"
 ignore_missing_imports = true
 exclude = ["tests/"]
 disallow_untyped_defs = true