initTerminal() creates the ResizeObserver on #terminalContainer once per page,
and _resetAllAppState() (run by handleInit on EVERY SSE init, page load
included) disconnected and dropped it. From the first init on, only a window
resize refit the terminal, so anything that resized just the terminal box left
xterm at its old row count with the bottom rows clipped behind the toolbar.
Pre-existing since the March app.js module split, but this release makes it
constant: #538's state rows grow and shrink the header whenever a session
starts or stops working, and #544 reserves lineage room when the first child
appears. Measured on the beta: header 115 -> 170 px, container 743 -> 688 px,
xterm stayed at 35 rows (32 fit) until a tab switch. initTerminal() already
disconnects any previous observer before creating one, so the reset has
nothing to clean up.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
