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/lib/server/api.ts

@@ -0,0 +1,69 @@
+import createClient from 'openapi-fetch';
+import { error, fail, redirect, type ActionFailure } from '@sveltejs/kit';
+import type { paths } from '$lib/api/schema';
+import type { SessionUser } from '$lib/types';
+import { apiConfig } from '$lib/server/config';
+
+interface ApiClientOptions {
+	fetch: typeof fetch;
+	accessToken?: string;
+}
+
+export function createApiClient({ fetch, accessToken }: ApiClientOptions) {
+	return createClient<paths>({
+		baseUrl: apiConfig.baseUrl,
+		fetch,
+		headers: accessToken ? { Authorization: `Bearer ${accessToken}` } : undefined
+	});
+}
+
+export function requireUser(locals: App.Locals, url: URL): SessionUser {
+	if (!locals.user)
+		redirect(302, `/login?returnTo=${encodeURIComponent(url.pathname + url.search)}`);
+	return locals.user;
+}
+
+export function requireAccessToken(locals: App.Locals, message = 'Inicia sesión.'): string {
+	if (!locals.accessToken) error(401, message);
+	return locals.accessToken;
+}
+
+export function requireAccessTokenAction(
+	locals: App.Locals,
+	message = 'Inicia sesión.'
+): string | ActionFailure<{ message: string }> {
+	return locals.accessToken ?? fail(401, { message });
+}
+
+export function unwrapOrError<T>(
+	result: { data?: T; error?: unknown; response?: Response },
+	message: string,
+	status?: number
+): T {
+	if (result.error || result.data === undefined) {
+		error(status ?? result.response?.status ?? 502, message);
+	}
+	return result.data;
+}
+
+export function unwrapOrFail(
+	result: { error?: unknown },
+	message: string
+): ActionFailure<{ message: string }> | undefined {
+	return result.error ? fail(502, { message }) : undefined;
+}
+
+export async function playlistCoverTrackIds(
+	api: ReturnType<typeof createApiClient>,
+	playlistIds: string[]
+): Promise<Record<string, string[]>> {
+	const covers = await Promise.all(
+		playlistIds.map(async (playlistId) => {
+			const { data: tracks } = await api.GET('/playlists/{playlistId}/tracks', {
+				params: { path: { playlistId }, query: { pageNumber: 1, pageSize: 4 } }
+			});
+			return [playlistId, tracks?.items.map((t) => t.id) ?? []] as const;
+		})
+	);
+	return Object.fromEntries(covers);
+}