## Summary
Adds support for loading templates via URL query parameters. Users can
now share direct links to templates.
To test:
1. checkout this branch
2. start dev server on port 5173
3. go to http://localhost:5173/?template=image_qwen_image_edit_2509
**Examples:**
- `/?template=default` - Loads template with default source
- `/?template=flux_simple&source=custom` - Loads from custom source
Includes error handling with toast notifications for invalid templates
and comprehensive test coverage.
---------
Co-authored-by: Christian Byrne <c.byrne@comfy.org>