feat: Handle steer tool results with approval requests

[lan17]

Summary

• add configurable steerBehavior support with requireApproval as the default
• map tool-step steer matches to OpenClaw requireApproval responses while keeping deny as a hard block
• document the new behavior and extend tests for steer approval, steer blocking, precedence, and guidance fallback

Verification

• npm run lint
• npm run typecheck
• npm test
• npm run coverage

[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.66667% with 4 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/agent-control-plugin.ts	91.66%	1 Missing and 3 partials ⚠️

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