Enhance file size validation and limits

Currently, the GUI accepts APK and IPA files without any size restrictions, which can lead to several problems:

• Large files can cause memory issues during upload
• Excessive storage usage in MinIO
• Potential timeout issues during processing
• Poor user experience with no upload progress indication

Technical Requirements:

• Backend Validation (Python/FastAPI):
• Add configurable file size limit (default: 100MB, configurable via environment variable)
• Implement file size check in the /upload endpoint before MinIO upload
• Add proper error handling with descriptive messages
• Log file size information for monitoring

Frontend Enhancement (HTML/JavaScript):

• Display file size in the upload interface
• Add client-side size validation before upload
• Show upload progress bar for large files
• Display remaining upload time estimate

Configuration:

• Add MAX_FILE_SIZE_MB environment variable
• Update Helm charts to include the new environment variable
• Document the configuration option

Acceptance Criteria:

[ ] File size validation implemented in backend (configurable via env var) [ ] Clear error messages for oversized files ("File too large. Maximum size: 100MB") [ ] Frontend displays file size and upload progress [ ] Client-side validation prevents unnecessary uploads [ ] Documentation updated with size limits and configuration [ ] Helm charts updated with new environment variable [ ] Tested with files of various sizes (small, medium, large, oversized)

Files to Modify:

• gui/webapp/main.py - Backend validation
• gui/webapp/templates/index.html - Frontend enhancements
• gui/values.yaml - Helm configuration
• gui/templates/webapp-deployment.yaml - Environment variables
• documentation/markdown/gui-setup.md - Documentation

GLHF :)