Fix AI tools and My Library, add U2net background removal

- Fix My Library: Add CSS styling for library browser, items now visible
- Integrate My Library into Shapes tool with tabbed interface
- Improve AI Inpaint: Add transform mode for scaling/sizing selections
- Add helpful guidance explaining inpaint vs transform modes
- Add U2net as alternative background removal (avoids rembg issues)
- Create U2net model definition and download script
- Improve Caddyfile with multiple options and troubleshooting guide

Note: Brush Select (AI Paint) tool was already implemented and working.

https://claude.ai/code/session_01CLedz6CanT9t46KBvng3vz

frontend/src/js/modules/file/my_library.js

@@ -334,7 +334,7 @@ class File_my_library_class {
             title: 'My Library (' + assets.length + ' assets)',
             params: [],
             html: html,
-            className: 'library-dialog',
+            className: 'wide',
             on_load: function(el) {
                 // Add click handlers
                 el.querySelectorAll('.insert-btn').forEach(function(btn) {