Switching tabs used to unmount the active view; a terminal's unmount sent
the tab-close frame, killing its pty, and switching back respawned a fresh
shell. Every tab now stays mounted and inactive ones are display:none: a
terminal keeps its WebSocket + pty + scrollback, an editor keeps its
CodeMirror view and unsaved draft, explorer/git keep their data. The close
frame now fires only when a tab is truly closed (close button, middle
click, pane removal). Re-shown terminals re-fit via the existing
ResizeObserver; editors re-measure via CodeMirror's own observer.
Menghuan1918
f4b86770d0