test: add integration tests for all modules

- Add pytest-asyncio dev dependency and configure asyncio_mode=auto
- Add filterwarnings to suppress third-party PydanticDeprecatedSince20
- Add conftest.py with shared fixtures (project_dir, write_config, etc.)
- Add test_config.py: YAML loading, target type inference, model resolution
- Add test_graph.py: DAG construction, cycle detection, build ordering
- Add test_state.py: hash functions, state persistence, dirty checking
- Add test_builder.py: full build pipeline with FakeProvider, incremental
  builds, selective builds, error isolation, dependency cascading
- Add test_providers.py: ImageProvider and TextProvider with mocked clients
- Add test_cli.py: build/clean/graph commands via typer CliRunner
- All 94 tests pass with 0 basedpyright warnings

pyproject.toml

@@ -20,9 +20,16 @@ bulkgen = "bulkgen.cli:app"
 requires = ["hatchling"]
 build-backend = "hatchling.build"
 
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+filterwarnings = [
+    "ignore::pydantic.warnings.PydanticDeprecatedSince20",
+]
+
 [dependency-groups]
 dev = [
     "basedpyright>=1.38.0",
     "pytest>=9.0.2",
+    "pytest-asyncio>=0.25.0",
     "ruff>=0.15.1",
 ]