feat(pipeline): add unified pipeline architecture with Stage abstraction

- Add engine/pipeline/ module with Stage ABC, PipelineContext, PipelineParams
- Stage provides unified interface for sources, effects, displays, cameras
- Pipeline class handles DAG-based execution with dependency resolution
- PipelinePreset for pre-configured pipelines (demo, poetry, pipeline, etc.)
- Add PipelineParams as params layer for animation-driven config
- Add StageRegistry for unified stage registration
- Add sources_v2.py with DataSource.is_dynamic property
- Add animation.py with Preset and AnimationController
- Skip ntfy integration tests by default (require -m integration)
- Skip e2e tests by default (require -m e2e)
- Update pipeline.py with comprehensive introspection methods

tests/conftest.py

@@ -0,0 +1,36 @@
+"""
+Pytest configuration for mainline.
+"""
+
+import pytest
+
+
+def pytest_configure(config):
+    """Configure pytest to skip integration tests by default."""
+    config.addinivalue_line(
+        "markers",
+        "integration: marks tests as integration tests (require external services)",
+    )
+    config.addinivalue_line("markers", "ntfy: marks tests that require ntfy service")
+
+
+def pytest_collection_modifyitems(config, items):
+    """Skip integration/e2e tests unless explicitly requested with -m."""
+    # Get the current marker expression
+    marker_expr = config.getoption("-m", default="")
+
+    # If explicitly running integration or e2e, don't skip them
+    if marker_expr in ("integration", "e2e", "integration or e2e"):
+        return
+
+    # Skip integration tests
+    skip_integration = pytest.mark.skip(reason="need -m integration to run")
+    for item in items:
+        if "integration" in item.keywords:
+            item.add_marker(skip_integration)
+
+    # Skip e2e tests by default (they require browser/display)
+    skip_e2e = pytest.mark.skip(reason="need -m e2e to run")
+    for item in items:
+        if "e2e" in item.keywords and "integration" not in item.keywords:
+            item.add_marker(skip_e2e)

tests/test_ntfy_integration.py

@@ -6,7 +6,11 @@ import json
 import time
 import urllib.request
 
+import pytest
 
+
+@pytest.mark.integration
+@pytest.mark.ntfy
 class TestNtfyTopics:
     def test_cc_cmd_topic_exists_and_writable(self):
         """Verify C&C CMD topic exists and accepts messages."""