Live portal: rename streams (tab double-click, persisted per browser) and name tab groups (header slot, session)

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

live/src/GroupLabel.jsx

@@ -0,0 +1,22 @@
+import React, { useEffect, useRef, useState } from 'react'
+import { names } from './names.js'
+
+// Left end of every tab bar: an editable group name (double-click). Session-only.
+export default function GroupLabel({ group }) {
+  const id = group.id
+  const name = names.use(s => s.groups[id])
+  const [editing, setEditing] = useState(false)
+  const [draft, setDraft] = useState('')
+  const ref = useRef(null)
+  useEffect(() => { if (editing) { ref.current?.focus(); ref.current?.select() } }, [editing])
+  const start = e => { e.stopPropagation(); setDraft(name || ''); setEditing(true) }
+  const commit = () => { if (!editing) return; names.renameGroup(id, draft.trim()); setEditing(false) }
+  return (
+    <div className="grouplabel" title="double-click to name this group" onDoubleClick={start} onPointerDown={e => e.stopPropagation()}>
+      {editing
+        ? <input ref={ref} value={draft} placeholder="group name" onChange={e => setDraft(e.target.value)} onBlur={commit}
+                 onKeyDown={e => { e.stopPropagation(); if (e.key === 'Enter') commit(); if (e.key === 'Escape') setEditing(false) }} />
+        : <span className={name ? 'gname' : 'hint'}>{name || '＋ name'}</span>}
+    </div>
+  )
+}