Add an overlay soundboard and fix playback command bugs.

Stop was advancing the queue, history overwrote the day file, and slash commands often never replied; soundboard clips now mix on top of the current track.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/global.d.ts

@@ -20,3 +20,12 @@ type HistoryObject = {
     url?: string,
 }
 
+type SoundboardSound = {
+    id: string
+    description: string
+    emoji: string
+    path: string
+    user: string
+    createdAt: number
+}
+