test: bootstrap pytest environment for backend

surfsense_backend/pyproject.toml

@@ -70,6 +70,21 @@ dependencies = [
 [dependency-groups]
 dev = [
     "ruff>=0.12.5",
+    "pytest>=8.0",
+    "pytest-asyncio>=0.25",
+    "pytest-mock>=3.14",
+]
+
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+asyncio_default_fixture_loop_scope = "session"
+testpaths = ["tests"]
+markers = [
+    "unit: pure logic tests, no DB or external services",
+    "integration: tests that require a real PostgreSQL database",
+]
+filterwarnings = [
+    "ignore::UserWarning:chonkie",
 ]
 
 [tool.ruff]