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/src/routes/+page.server.ts

@@ -0,0 +1,48 @@
+import type { PageServerLoad, Actions } from './$types';
+import { createApiClient, playlistCoverTrackIds } from '$lib/server/api';
+import { fetchYoutubeFiller, shuffle } from '$lib/server/youtube';
+import { addTrackAction, addYouTubeToPlaylistAction } from '$lib/server/playlistActions';
+import { HOME_LATEST_PAGE_SIZE, YOUTUBE_FILLER_LIMIT } from '$lib/config';
+import { pickGreeting } from '$lib/server/greeting';
+
+export const load: PageServerLoad = async ({ locals, fetch }) => {
+	const api = createApiClient({ fetch, accessToken: locals.accessToken ?? undefined });
+
+	const latestPromise = api.GET('/tracks', {
+		params: { query: { pageNumber: 1, pageSize: HOME_LATEST_PAGE_SIZE } }
+	});
+	const playlistsPromise = locals.user
+		? api.GET('/playlists/users/{userId}', {
+				params: { path: { userId: locals.user.sub }, query: { pageNumber: 1, pageSize: 12 } }
+			})
+		: Promise.resolve({ data: undefined });
+	const recentlyPlayedPromise = locals.user
+		? api.GET('/users/{id}/listening-history', { params: { path: { id: locals.user.sub } } })
+		: Promise.resolve({ data: undefined });
+
+	const [latest, playlists, recentlyPlayed] = await Promise.all([
+		latestPromise,
+		playlistsPromise,
+		recentlyPlayedPromise
+	]);
+	const playlistItems = playlists.data?.items ?? [];
+	const trackIds = await playlistCoverTrackIds(
+		api,
+		playlistItems.map((p) => p.id)
+	);
+
+	return {
+		greeting: pickGreeting(new Date().getHours()),
+		latest: shuffle((latest.data?.items ?? []).map((track) => ({ kind: 'local' as const, track }))),
+		latestHasNext: Boolean(latest.data?.hasNextPage),
+		youtubeFiller: fetchYoutubeFiller(api, locals.accessToken, YOUTUBE_FILLER_LIMIT),
+		playlists: playlistItems,
+		trackIds,
+		recentlyPlayed: recentlyPlayed.data ?? []
+	};
+};
+
+export const actions: Actions = {
+	addTrack: addTrackAction,
+	addYouTubeToPlaylist: addYouTubeToPlaylistAction
+};