Remove comments from backend and web-player source

Strip //, /* */ and XML doc comments from all backend .cs files, and
JS/TS/CSS/HTML comments from web-player source (.ts, .svelte, .css),
per the project's no-comments convention.

web-player/src/lib/recentlyPlayed.ts

@@ -1,9 +1,5 @@
 import { player, toQueueItems, type ApiTrackLike, type QueueItem } from '$lib/player/player.svelte';
 
-/**
- * Merges the in-memory session history (tracks played since the page loaded)
- * with the server-side listening history, de-duplicated by id and capped at `limit`.
- */
 export function mergeRecentlyPlayed(history: ApiTrackLike[], limit: number): QueueItem[] {
 	const seen = new Set<string>();
 	const merged: QueueItem[] = [];