reafctor: Rely only on the database for themes

This commit makes it so that a user's theme will only be pulled from the
database rather than from a weird mix of cookies and the database. This
fixes some issues with themes rendering weirdly.

app/components/Settings/AppearanceSettings.vue

@@ -1,6 +1,5 @@
 <script setup lang="ts">
-const { settings, updateSettings } = await useUserSettings();
-const { colorScheme } = useTheme();
+const { colorScheme, settings, updateSettings } = await useUserSettings();
 
 const accents = ['violet', 'volcano', 'lime', 'sky', 'coral', 'emerald', 'amber', 'rose', 'cyan', 'indigo', 'magenta'];
 const neutrals = ['zinc', 'slate', 'obsidian'];