refactor: rename frontend/ to web-player/ and format with prettier

Updates the compose build context, the Dockerfile header, the package
name and the docs. The compose service and container keep the name
frontend/musify-frontend, since nginx routes to http://frontend:3000.

The source files also carry the first prettier pass, so the rename and
the reformat land together for them.

web-player/vite.config.ts

@@ -0,0 +1,20 @@
+import tailwindcss from '@tailwindcss/vite';
+import adapter from '@sveltejs/adapter-node';
+import { sveltekit } from '@sveltejs/kit/vite';
+import { defineConfig } from 'vite';
+
+export default defineConfig({
+	ssr: {
+		noExternal: ['@lucide/svelte']
+	},
+	plugins: [
+		tailwindcss(),
+		sveltekit({
+			compilerOptions: {
+				runes: ({ filename }) =>
+					filename.split(/[/\\]/).includes('node_modules') ? undefined : true
+			},
+			adapter: adapter()
+		})
+	]
+});