[antonisloukis]

Summary

Replaces the minimal README with complete project documentation for RunbookProof.

Changes

• Added a clear project overview and problem statement
• Added CI and Code Scanning workflow badges
• Documented installation and quick-start commands
• Documented file and directory scanning
• Documented text, JSON, and SARIF output
• Documented -o and --output
• Listed all built-in verification packs
• Documented process exit codes
• Added GitHub Code Scanning integration example
• Added architecture overview
• Added development and validation commands
• Added roadmap, security model, and license sections
• Clarified the current pre-alpha project status

Validation

• RunbookProof scanned the new README
• 899 tests passed
• Total coverage: 93.25%
• Ruff formatting check passed
• Ruff linting passed
• MyPy passed
• git diff --check passed