feat(web): surface "Start radio" in the track kebab menu

Radio was fully wired (playRadio → /api/radio + 80% auto-refresh) but its
only entry point was TrackRow's inline 📻 button, so it was unreachable from
the kebab — i.e. missing on the Most Played compact cards and the mini-player.
Add a "Start radio" item to TrackMenu, shown even under hideQueueActions since
reseeding a station from the current track is meaningful there.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/lib/components/TrackMenu.svelte

@@ -3,6 +3,7 @@
     MoreVertical,
     ListPlus,
     Plus,
+    Radio,
     Heart,
     HeartOff,
     ListMusic,
@@ -24,7 +25,7 @@
   import { createLikedIdsQuery, likeEntity, unlikeEntity } from '$lib/api/likes';
   import { createMyQuarantineQuery, unflagTrack } from '$lib/api/quarantine';
   import { qk } from '$lib/api/queries';
-  import { playNext, enqueueTrack } from '$lib/player/store.svelte';
+  import { playNext, enqueueTrack, playRadio } from '$lib/player/store.svelte';
   import type { TrackRef } from '$lib/api/types';
 
   let {
@@ -87,6 +88,11 @@
     closeAll();
   }
 
+  function onStartRadio() {
+    playRadio(track.id);
+    closeAll();
+  }
+
   async function onToggleLike() {
     closeAll();
     if (liked) {
@@ -168,6 +174,14 @@
         <TrackMenuDivider />
       {/if}
 
+      <!-- Start radio is always offered, even on the now-playing surfaces
+           (hideQueueActions) — reseeding the queue as a radio station from
+           the current track is meaningful where "play next" / "add to queue"
+           are not. Mirrors TrackRow's inline 📻 button via playRadio(). -->
+      <TrackMenuItem icon={Radio} label="Start radio" onclick={onStartRadio} />
+
+      <TrackMenuDivider />
+
       <TrackMenuItem
         icon={liked ? HeartOff : Heart}
         label={liked ? 'Unlike' : 'Like'}