App-driven paste (context menu / Ctrl+Shift+V) writes straight to the pty,
bypassing xterm's onData, and xterm-native paste arrives wrapped in
bracketed-paste markers that the buffer guards dropped. Either way a pasted
'cd D:\path' was recorded as the bare 'cd' typed before it, so the pane's
directory memory silently stayed home. Track submitted lines from pasted
text and strip bracketed-paste markers in the line buffer.