feat(ui-flow): Phase 683 slash-modal-open IPC with composer blur

Handle slash-modal-open by pushing state and emitting slash-modal-opened.

Co-authored-by: Cursor <[email protected]>

index.js

@@ -2384,6 +2384,11 @@ async function dispatchUiMessage (platform, msg, hooks = {}) {
     send({ type: 'member-roles-modal-opened' })
     return true
   }
+  if (t === 'slash-modal-open') {
+    pushState()
+    send({ type: 'slash-modal-opened' })
+    return true
+  }
   if (t === 'revoke-invite') {
     await platform.revokeInvite(msg.code)
     pushState()