Live portal: custom layouts are left alone — new streams chime and wait in a draggable tray; Arrange re-grids and returns to auto

layout store (auto/custom + pending), marked custom on manual move (onDidMovePanel outside arrange), sash drag,
stream/group rename. Tray chips: HTML5 drag accepted via onUnhandledDragOver/onDidDrop (position -> direction),
click = new column. WebAudio two-note chime. Gateway page instructions updated. Verified headless (custom vs auto).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

live/src/Tray.jsx

@@ -0,0 +1,23 @@
+import React from 'react'
+import { layout } from './layout.js'
+import { streamLabel } from './names.js'
+
+export const STREAM_MIME = 'application/x-vanguard-stream'
+
+// Zero-height when empty. New streams in a custom layout wait here: drag a chip into the dock (any edge, any window,
+// or onto a tab bar to stack), or click it to add it as a new column on the right.
+export default function Tray({ onPlace }) {
+  const pending = layout.use(s => s.pending)
+  if (!pending.length) return null
+  return (
+    <div className="tray" title="new streams — drag into the layout, or click to add on the right">
+      {pending.map(s => (
+        <div key={s.id} className="chip" draggable
+             onDragStart={e => { e.dataTransfer.setData(STREAM_MIME, s.id); e.dataTransfer.setData('text/plain', s.id); e.dataTransfer.effectAllowed = 'move' }}
+             onClick={() => onPlace(s.id, { direction: 'right' })}>
+          <span className="blink">●</span> {streamLabel(s.id, s)}
+        </div>
+      ))}
+    </div>
+  )
+}