feat: Improved DebugWizard UX with card-based file selection

Major UX improvements:
- Three large, colorful cards for file selection:
  - Blue card: Select individual files (with drag & drop)
  - Yellow card: Select entire folder
  - Green card: Paste code directly
- Loading spinner while processing files
- Improved tree view with SVG icons and better styling
- Green success state when files are uploaded
- Clear visual feedback for auto-filtered files
- Back button to return from paste mode
- Better responsive design

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: 2 people