fix(calls): explain when the soundboard is not allowed in a voice channel (EC #47)

The fork now refuses a clip it cannot publish (audio-only rooms grant
only the microphone source) with reason "not_permitted". Say "The
soundboard isn't available in this voice channel" instead of the
generic error. Older forks are unaffected.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/features/call/CallSoundboard.tsx

@@ -50,6 +50,14 @@ type FlatClip = {
  * A management toggle reveals the pack editors (personal + this room, if
  * permitted). Space-wide packs are managed from Space settings.
  */
+/** [EC#13, EC#47] Why the fork refused to play a clip, for the user. */
+export const soundboardRefusalText = (reason: string | undefined): string => {
+  if (reason === 'muted') return 'Unmute your microphone to play a soundboard clip.';
+  if (reason === 'not_permitted')
+    return "The soundboard isn't available in this voice channel (only microphone audio is allowed here).";
+  return 'Could not play that clip.';
+};
+
 export function CallSoundboard({ callEmbed }: CallSoundboardProps) {
   const mx = useMatrixClient();
   const { room } = callEmbed;
@@ -122,13 +130,10 @@ export function CallSoundboard({ callEmbed }: CallSoundboardProps) {
           .catch(() => undefined);
         const result = await callEmbed.control.injectAudio(url, vol, clipBytes);
         if (!result.played) {
-          // [EC#13] Refused fork-side (only reason today: local mic muted) —
+          // [EC#13, EC#47] Refused fork-side (mic muted, or the room's token
+          // only allows the microphone source, as in audio-only rooms) —
           // don't play it locally either, or the user would think it went out.
-          setError(
-            result.reason === 'muted'
-              ? 'Unmute your microphone to play a soundboard clip.'
-              : 'Could not play that clip.',
-          );
+          setError(soundboardRefusalText(result.reason));
           done();
           return;
         }