Apply the theme from PageSettings in JS, before the first paint

wwwroot/js/theme.js now picks the theme. It sets data-theme (neo-light or
neo-dark, or none when the OS decides) and the hue and chroma variables on
<html>, using the same flag precedence as the old CascadingState branches. It
also keeps <meta name="theme-color"> in sync. Because it runs in <head> from the
settings saved in localStorage, a reload no longer flashes the default palette
before Blazor boots. With system theming it also follows the OS when the colour
scheme changes.

CascadingState loses its ~200 lines of generated <style> and <Meta> tags. It now
calls AppStatusService.ApplyTheme on load and whenever the settings change. The
--fa-* icon colour variables are gone; nothing read them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

Services/AppStatusService.cs

@@ -1,4 +1,6 @@
-using Microsoft.JSInterop;
+using decePubClient.Models;
+
+using Microsoft.JSInterop;
 
 namespace decePubClient.Services;
 
@@ -44,6 +46,9 @@ public class AppStatusService
 			JsSyncRuntime.InvokeVoid("reloadPage");
 		}
 
+		// wwwroot/js/theme.js
+		public void ApplyTheme(PageSettings pageSettings) => JsSyncRuntime.InvokeVoid("neoTheme.apply", pageSettings);
+
 		public bool IsMobileMedia() => JsSyncRuntime.Invoke<bool>("isMobileMedia");
 
 		public bool CanShare() => JsSyncRuntime.Invoke<bool>("canShareStuff");