#8079 improvement(ui): reuse avatars for owners and members

Summary

• Use the existing Avatar family for owner and member photos, initials and failed-image fallback.
• Give the existing xs size 8px initials centrally. Preserve the 14px footprint, image alt/referrer behavior, other sizes and explicit fallback overrides.

Type of Change

• Refactor / maintainability improvement

Testing

• Full workspace type checks, lint, repository audits (including import and API validation), generators and docs checks pass.
• Complete EMCN test suite and relevant existing consumer suites pass.
• Before/after browser fixtures cover light/dark styling, narrow layouts and the affected interaction patterns. Fixtures are isolated controls, not full authenticated product flows.
• No landing-page changes or audit tooling included.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)