Opening the app no longer auto-creates a blank tab or auto-restores/discovers
sessions as tabs. Instead it lands on a launcher (session chooser): a grid of the
host's running sessions as live preview thumbnails — pick one to open (replays its
full scrollback), or '+ New session'. Closing the last tab returns to the chooser.
- public/launcher.ts: mountLauncher() renders the chooser into the terminal area
(live xterm thumbnails via /live-sessions + /preview, 5s refresh), New session +
Manage link
- tabs.ts: drop restore()/syncLiveSessions() auto-tab behavior; constructor lands
on the launcher; rebuild() toggles launcher when tab count is 0; closeTab no
longer spawns a blank tab
- style.css: .launcher chrome (reuses the .mg-* card/grid/thumbnail styles)
Verified: fresh load → 0 tabs, chooser with thumbnails; Open → tab + chooser
hides; close last tab → chooser returns. 228 tests green, tsc + build clean.
