TerminalView now emits TitleChanged/Exited and owns session teardown
(Msg::Shutdown on removal, Drop as backstop). TerminalPanel adapts the
terminal to the dock Panel contract with a title_suffix close button,
since a root-level TabPanel never renders its own. NebulaWorkspace
wires TitleBar + tabs with ctrl-shift-t/w hotkeys (passed through the
terminal key handler), closes tabs on shell exit, and quits when the
last tab closes. The component gallery moves to a secondary window.
kuddev
6d794f2f1c