test: update test fixtures to use @with_session decorator

- Replace manual session management in test fixtures with @with_session decorator
- Simplify async test fixtures by removing explicit session handling
- Update dependencies in pyproject.toml and uv.lock

server/pyproject.toml

@@ -46,6 +46,7 @@ dev = [
     "black>=24.1.1",
     "stamina>=23.1.0",
     "pyinstrument>=4.6.1",
+    "pytest-async-sqlalchemy>=0.2.0",
 ]
 tests = [
     "pytest-cov>=4.1.0",
@@ -117,7 +118,9 @@ DATABASE_URL = "postgresql+asyncpg://test_user:test_password@localhost:15432/ref
 addopts = "-ra -q --disable-pytest-warnings --cov --cov-report html -v"
 testpaths = ["tests"]
 asyncio_mode = "auto"
+asyncio_debug = true
 asyncio_default_fixture_loop_scope = "session"
+asyncio_default_test_loop_scope = "session"
 markers = [
     "model_api: tests for the unified model-serving HTTP API (backend- and hardware-agnostic)",
 ]