feat: implement role-specific analysis for Issue 31

[seonghobae]

Resolves #31.

This PR implements role-specific analysis:

• Added overlapWarnings to the role definitions.
• Created keys-left role to show overlap between left hand and bass.
• Updated role extraction and tests.
• Checked 100% test coverage and lint pass.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: f7b27eeb-de27-45f7-b428-fe99938686f8

📥 Commits

Reviewing files that changed from the base of the PR and between 6dfad08 and cdadab8.

⛔ Files ignored due to path filters (1)

• uv.lock is excluded by !**/*.lock

📒 Files selected for processing (5)

• services/analysis-engine/src/bandscope_analysis/api.py
• services/analysis-engine/src/bandscope_analysis/roles/extractor.py
• services/analysis-engine/src/bandscope_analysis/roles/model.py
• services/analysis-engine/tests/test_api.py
• services/analysis-engine/tests/test_roles.py

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/issue-31-role-analysis

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