Add collaboration compass tool

[sedge-bot]

Summary

• add a local-only collaboration compass tool for scoring human/AI collaboration feature ideas as reviewable Markdown cards
• add unittest coverage for complete and sparse idea inputs
• link the tool from README and CONTRIBUTING as a concrete path for issue Propose a feature that improves human-AI collaboration #2

Closes #2

Validation

• python3 -m unittest tools/collaboration-compass/test_compass.py -v
• python3 -m py_compile tools/collaboration-compass/compass.py tools/collaboration-compass/test_compass.py
• git diff --check
• /opt/sedge/.local/bin/uv run --extra dev pytest -q (14 passed)
• python3 scripts/pr_safety_lint.py --base origin/main --head HEAD (0 block, 2 warn: expected test fixture JSON write + subprocess CLI invocation)