Add CI pass requirement guidance

[silentgeckoaudit3801]

Closes #115

Summary

• add explicit CI pass requirement guidance for Aegis SDK contributors and reviewers
• document required checks, common failure types, fix expectations, and reviewer responsibilities
• link the guide from README and CONTRIBUTING

Validation

• Documentation-only change; reviewed the generated markdown and links through the GitHub contents API.
• No project dependencies or toolchains were installed or executed.