- tabs.ts: on open, syncLiveSessions() fetches /live-sessions and adds a tab for
each host session not already open → any device sees & mirrors everything
running on the host. Empty storage + no live sessions → one fresh tab.
activeSessionId() + openSession(id) helpers.
- share.ts: 🔗 toolbar button → QR + <origin>/?join=<id> for the active session.
- main.ts: ?join=<id> on load opens/focuses that shared session, then strips the
param. Mount share button (toolbar: 🔍 ⚙ ▦ 🕘 ⌨ 🔗📱).
- style.css: #sharemodal reuses the QR card/backdrop.
Verified in-browser: fresh device auto-discovered the host session and replayed
its scrollback; two concurrent clients (browser + ws) both received live output
(clientCount=2); share modal shows the join URL/QR.
