web-player: buttons (Button, IconButton, PlayButton)

Button: subtle variants (primary/secondary, left unchanged per the
user's call), glass (formerly secondaryOnGlow, with its own
font-normal), accent, strong (cta-strong/ink, replacing the `!`
overrides on the Home hero), danger. Uses the --color-btn* tokens
instead of bg-[var(--mf-btn-...)]. Radius unified to rounded-control.

IconButton: adds shape (square/round), size (xs/sm/md/lg), tone
(muted/subtle/plain), pressed (aria-pressed + text-accent),
href/reload (links), surface (permanent background + hover to
surface-hover instead of the generic `hover` alias, which matched
surface-2 and gave no contrast).

New PlayButton: a single place for the play/pause SVGs, strong/glass
variants, as="span" for non-interactive overlays. Replaces
TransportControls' main button, the MixTile overlay, and the "Top
result" circle in Explore.

Migrated to IconButton: close queue, "Create playlist" (Sidebar),
Like (TrackInfo, with pressed), queue (PlayerExtras), back (TopBar),
login (MobileHeader), and the row actions in tables (remove/add, size
xs). BackLink uses size-icon-sm and drops a duplicate hover.

Decision (not blocking): remove TopBar's decorative "forward" button
and PlayerExtras' decorative AlignJustify icon (visually dead code).
TransportControls' buttons (shuffle/prev/next/repeat) are
deliberately left unmigrated: they currently have no background or
hit-box of their own, and IconButton always applies a fixed-size
box — migrating them would have added a visible hover pill that
couldn't be verified without Docker this session.

Verified with npm run check/build.

web-player/src/routes/(app)/explore/+page.svelte

@@ -1,6 +1,5 @@
 <script lang="ts">
 	import Music from '@lucide/svelte/icons/music';
-	import Play from '@lucide/svelte/icons/play';
 	import { player } from '$lib/player/player.svelte';
 	import { fetchAlbumQueueItems } from '$lib/albums';
 	import { fmtTime, fmtPlays } from '$lib/format';
@@ -11,6 +10,7 @@
 	import InfiniteScroll from '$lib/components/ui/InfiniteScroll.svelte';
 	import Artwork from '$lib/components/ui/Artwork.svelte';
 	import Avatar from '$lib/components/ui/Avatar.svelte';
+	import PlayButton from '$lib/components/ui/PlayButton.svelte';
 	import NowPlaying from '$lib/components/ui/NowPlaying.svelte';
 	import SearchResultRow from '$lib/components/ui/SearchResultRow.svelte';
 	import SectionHeading from '$lib/components/ui/SectionHeading.svelte';
@@ -339,11 +339,7 @@
 					{/if}
 				</div>
 
-				<span
-					class="grid h-11.5 w-11.5 shrink-0 place-items-center rounded-full bg-cta-strong text-ink transition group-hover/top:brightness-110"
-				>
-					<Play class="h-4 w-4" fill="currentColor" strokeWidth={0} />
-				</span>
+				<PlayButton as="span" size="lg" label="Reproducir" class="group-hover/top:brightness-110" />
 			{/snippet}
 
 			{#if topResult.kind === 'track'}