Custom themes and config overrides (#9)

Co-authored-by: Astra <me@astrra.space>
Reviewed-on: https://git.witchcraft.systems/scientific-witchery/pds-dash/pulls/9
Reviewed-by: Astra <me@astrra.space>
Co-authored-by: Ari <ariadna@hey.com>
Co-committed-by: Ari <ariadna@hey.com>

vite.config.ts

@@ -1,7 +1,11 @@
 import { defineConfig } from "vite";
 import { svelte } from "@sveltejs/vite-plugin-svelte";
+import { themePlugin } from "./theming";
 
 // https://vite.dev/config/
 export default defineConfig({
-  plugins: [svelte()],
+  plugins: [
+    themePlugin(),
+    svelte(),
+  ],
 });