refactor: modernize React component types

[aksOps]

Summary

• mark functional component props as Readonly across the React surface
• replace deprecated MutableRefObject and FormEvent types with RefObject and SubmitEvent
• resolve 29 Sonar maintainability findings without runtime behavior changes

Validation

• npm run build
• npm test (64 files, 902 tests passed)
• git diff --check

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud