fix: restore dark theme and fix theme script regex

Dark theme was set to "dim" in theme.config.ts while app.css registered
"sunset" as the prefersdark theme. The script's regex required a trailing
comma that didn't exist on the last property, causing silent failures.

src/theme.config.ts

@@ -3,5 +3,5 @@
 
 export const themeConfig = {
   light: "garden",
-  dark: "dim"
+  dark: "sunset"
 }