feat(web-player): add the albums pages

A grid of your albums with a create dialog, and a detail page with the
tracklist, inline editing and a picker that lists the songs you uploaded so
they can be dropped into the album. Covers reuse the playlist mosaic since an
album has no artwork of its own yet.

web-player/src/routes/(app)/albums/[id]/+page.server.ts

@@ -0,0 +1,110 @@
+import type { PageServerLoad, Actions } from './$types';
+import { fail, redirect } from '@sveltejs/kit';
+import {
+	createApiClient,
+	requireAccessTokenAction,
+	requireUser,
+	unwrapOrError,
+	unwrapOrFail
+} from '$lib/server/api';
+import { ALBUM_TRACKS_PAGE_SIZE, LIBRARY_PICKER_PAGE_SIZE } from '$lib/config';
+import { parseAlbumForm } from '$lib/server/albumForm';
+
+export const load: PageServerLoad = async ({ params, locals, url, fetch }) => {
+	const user = requireUser(locals, url);
+	const api = createApiClient({ fetch, accessToken: locals.accessToken ?? undefined });
+
+	const [albumRes, tracksRes, libraryRes] = await Promise.all([
+		api.GET('/albums/{id}', { params: { path: { id: params.id } } }),
+		api.GET('/albums/{albumId}/tracks', {
+			params: {
+				path: { albumId: params.id },
+				query: { pageNumber: 1, pageSize: ALBUM_TRACKS_PAGE_SIZE }
+			}
+		}),
+		api.GET('/tracks/users/{userId}', {
+			params: {
+				path: { userId: user.sub },
+				query: { pageNumber: 1, pageSize: LIBRARY_PICKER_PAGE_SIZE }
+			}
+		})
+	]);
+
+	const album = unwrapOrError(albumRes, 'Álbum no encontrado.', 404);
+
+	const tracks = tracksRes.data?.items ?? [];
+	const inAlbum = new Set(tracks.map((track) => track.id));
+	const library = (libraryRes.data?.items ?? []).filter(
+		(track) => track.source === 'Local' && !inAlbum.has(track.id)
+	);
+
+	return { album, tracks, library, isOwner: Number(album.ownerUserId) === Number(user.sub) };
+};
+
+export const actions: Actions = {
+	addTrack: async ({ request, params, locals, fetch }) => {
+		const accessToken = requireAccessTokenAction(locals);
+		if (typeof accessToken !== 'string') return accessToken;
+
+		const trackId = String((await request.formData()).get('trackId') ?? '');
+		if (!trackId) return fail(400, { message: 'Falta la canción.' });
+
+		const api = createApiClient({ fetch, accessToken });
+		const result = await api.POST('/albums/{albumId}/tracks/{trackId}', {
+			params: { path: { albumId: params.id, trackId } }
+		});
+		const failure = unwrapOrFail(result, 'No se pudo añadir la canción.');
+		if (failure) return failure;
+		return { added: true };
+	},
+
+	removeTrack: async ({ request, params, locals, fetch }) => {
+		const accessToken = requireAccessTokenAction(locals);
+		if (typeof accessToken !== 'string') return accessToken;
+
+		const trackId = String((await request.formData()).get('trackId') ?? '');
+		if (!trackId) return fail(400, { message: 'Falta la canción.' });
+
+		const api = createApiClient({ fetch, accessToken });
+		const result = await api.DELETE('/albums/{albumId}/tracks/{trackId}', {
+			params: { path: { albumId: params.id, trackId } }
+		});
+		const failure = unwrapOrFail(result, 'No se pudo quitar la canción.');
+		if (failure) return failure;
+		return { removed: true };
+	},
+
+	edit: async ({ request, params, locals, fetch }) => {
+		const accessToken = requireAccessTokenAction(locals);
+		if (typeof accessToken !== 'string') return accessToken;
+
+		const parsed = parseAlbumForm(await request.formData());
+		if ('failMessage' in parsed) return fail(400, { message: parsed.failMessage });
+
+		const api = createApiClient({ fetch, accessToken });
+		const result = await api.PUT('/albums/{albumId}', {
+			params: { path: { albumId: params.id } },
+			body: {
+				newTitle: parsed.body.title,
+				newDescription: parsed.body.description,
+				newReleaseYear: parsed.body.releaseYear
+			}
+		});
+		const failure = unwrapOrFail(result, 'No se pudo actualizar el álbum.');
+		if (failure) return failure;
+		return { edited: true };
+	},
+
+	delete: async ({ params, locals, fetch }) => {
+		const accessToken = requireAccessTokenAction(locals);
+		if (typeof accessToken !== 'string') return accessToken;
+
+		const api = createApiClient({ fetch, accessToken });
+		const result = await api.DELETE('/albums/{albumId}', {
+			params: { path: { albumId: params.id } }
+		});
+		const failure = unwrapOrFail(result, 'No se pudo eliminar el álbum.');
+		if (failure) return failure;
+		redirect(303, '/albums');
+	}
+};