Each connection now lives in its own ServerTab with its own tree, info
and chat views plus its own mic-mute, deafen, away and commander state.
MainFrame keeps only the shell (menus, toolbar, status bar) and shows
one tab at a time; the tab bar below the toolbar appears once a second
server is open.
Incoming voice from every connection mixes into the same output — each
connection already renders one line per speaker. Capture is exclusive:
a connection only opens the microphone while it holds it, and a toolbar
button moves it to the visible tab. The mic follows a disconnect to
another connected tab, and push-to-talk drives whoever holds it.
Startup bookmarks are no longer mutually exclusive: every flagged
bookmark opens its own tab.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>