refactor(frontend): modularize angular and javascript documentation for Vibe Coding optimization

[beginwebdev2002]

Resolved Git merge conflicts in frontend/angular/readme.md and frontend/javascript/readme.md. The conflict resolution accepted the main branch's modularized version to prevent "walls of text", ensuring links point to specialized topics like advanced-performance.md and expert-niche.md. Cleaned up temporary files created during the resolution process.

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PR created automatically by Jules for task 17094275205959628460 started by @beginwebdev2002

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