docs: add comprehensive uninstall & fresh install guide

New guide includes:
- Complete uninstall steps (warp-cli, daemon, app, config files)
- Fresh install walkthrough
- Troubleshooting common installation issues
- Nuclear option for complete removal
- Installation methods comparison
- Switching between installation methods
- Maintenance and auto-updates
- Verification scripts to confirm everything works
- Checklist for successful installation

Covers all scenarios:
✅ Fresh install on clean system
✅ Removing old installation
✅ Troubleshooting install failures
✅ Switching from old tap to new
✅ Switching between install methods
✅ Complete removal if needed

Includes bash scripts for:
- Nuclear cleanup option
- Automated verification
- Clear step-by-step instructions

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Author: ashu17706