[calesthio]

Summary

Adds a focused GitHub Actions CI workflow for OpenMontage pull requests and pushes to main.

The workflow:

• checks out the repository
• installs FFmpeg for media/QA tests
• sets up Python 3.11 with pip dependency caching
• installs development dependencies through make install-dev
• runs the existing lint smoke target with make lint
• runs the full pytest suite through make test

Related issue

Closes #141

Changes

• Added .github/workflows/ci.yml.
• Added numpy to core requirements because discovered tools import it during clean installs.
• Updated the TTS provider contract expectation so the current Doubao provider is represented in the catalog baseline.
• Added the missing character-animation render_runtime_selection/present-both runtime guidance required by the existing runtime presentation contract.

Review guide alignment

I kept this separate from PR #155's tutorial, reviewer-guide, and Remotion changes per docs/PR_REVIEW_GUIDE.md scope-hygiene guidance. This PR is limited to CI plus the small baseline fixes needed so the new CI check is green on current main.

Testing

• python -c "from pathlib import Path; import yaml; data=yaml.safe_load(Path('.github/workflows/ci.yml').read_text()); print(data.get('name'))"
• python -m py_compile tools/base_tool.py tools/tool_registry.py tools/cost_tracker.py tools/analysis/composition_validator.py
• python -m pytest tests/contracts -q -> 264 passed, 1 skipped
• python -m pytest tests/tools -q -> 77 passed
• python -m pytest tests -q -> 341 passed, 3 skipped

Note: local Windows environment does not have make, so I ran the underlying Python commands directly. The GitHub Actions runner uses Ubuntu, where make is available.