chore(docs): Update CONTRIBUTING.md

[brendan-kellam]

Summary by CodeRabbit

• Documentation
  • Updated Contributing guidelines with expanded sections covering licensing requirements, contributor policies, development setup expectations, and pull request submission guidelines.

[coderabbitai]

Caution

Review failed

The pull request is closed.

Walkthrough

The CONTRIBUTING.md documentation was updated to replace a brief "Build from source" note with a comprehensive "Contributing to Sourcebot" section. The new content includes guidance on licensing distinctions (core vs. enterprise edition), contributor policies, development expectations, and pull request requirements. No code or executable behavior is modified.

Changes

Cohort / File(s)	Summary
Documentation CONTRIBUTING.md	Replaced "Build from source" note with expanded "Contributing to Sourcebot" section covering licensing guidance (core/ee), contributor policy, development expectations, and PR requirements.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch bkellam/updated-contributing

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[github-actions]

@brendan-kellam your pull request is missing a changelog!