ci: skip heavy/integration tests to reduce CI runtime

- Register 'integration' pytest mark in pyproject.toml to eliminate
  PytestUnknownMarkWarning across the test suite
- Add -m "not integration" and --ignore for external-service tests,
  notebook tests, comprehensive real-world tests, and API-key-dependent
  tests (Groq, Novita, Snowflake, Neptune, HF deepdive)
- Keeps fast unit tests: context, kg, semantic_extract, reasoning,
  pipeline, export, deduplication, parse, normalize, utils, provenance

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -28,4 +28,27 @@ jobs:
       - run: pip install build
       - run: python -m build
       - run: pip install -e ".[dev]"
-      - run: pytest tests/ -x -q
+      - run: |
+          pytest tests/ -x -q \
+            -m "not integration" \
+            --ignore=tests/cookbook \
+            --ignore=tests/integration \
+            --ignore=tests/graph_store \
+            --ignore=tests/vector_store \
+            --ignore=tests/visualization \
+            --ignore=tests/test_notebooks_plain.py \
+            --ignore=tests/test_notebooks_repro.py \
+            --ignore=tests/test_notebooks_simulation.py \
+            --ignore=tests/test_notebooks_verification.py \
+            --ignore=tests/test_notebook_15_export.py \
+            --ignore=tests/test_030_realworld_comprehensive.py \
+            --ignore=tests/test_030_context_graph_realworld_extended.py \
+            --ignore=tests/test_all_features.py \
+            --ignore=tests/test_semantic_extract_deepdive.py \
+            --ignore=tests/test_semantic_extract_deepdive_part2.py \
+            --ignore=tests/test_groq_integration.py \
+            --ignore=tests/test_novita_integration.py \
+            --ignore=tests/test_snowflake_ingestor.py \
+            --ignore=tests/test_amazon_neptune.py \
+            --ignore=tests/test_hf_deep_verify.py \
+            --ignore=tests/test_embedding_providers.py