Adds a Bell icon button to the topbar that sums chatUnreadCount +
queueCount and shows a single amber dot with the total. Click goes
to Chat if there are unread messages, otherwise to Approvals — the
scene most likely to be relevant. Per-tab badges on Approvals and
Chat tabs stay (they answer 'where' specifically), but operators who
just want 'do I have anything waiting' now get a single one-glance
signal in the topbar.
Title attr names the breakdown for accessibility. 31/31 vitest pass.
canvas-bot