Stemify iOS 1.1 and WebUI updates, repo restructure into desktop/ios/server/web

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

ios/TODO.md

@@ -0,0 +1,14 @@
+# iOS to-do
+
+Planned, not started.
+
+1. Album shuffle: random order of whole albums, tracks in order inside each (like Plexamp).
+2. Customizable stem presets: let the user edit and remove presets (No Drums, Rhythm, etc.) and add their own.
+3. Bug: a saved mix's stem selection carries over to the next track.
+4. Continuous preloading: user sets how many songs to preload in Settings, up to 50.
+5. Let the user hide options on the now-playing screen.
+6. CarPlay stem change text: show only the mix type instead of "Mix: <type>".
+7. Add Genre to the Library tab.
+8. Remove the "Only show songs with stems" setting, since sorting already covers it.
+9. Add a "No Stems" sort option.
+10. Optional donate buttons in Settings.