- editorLines now soft-wraps long logical lines at the box width (caret tracked
across wrapped rows) instead of overflowing/truncating
- alt+backspace deletes the word before the cursor (deleteWordBack)
- handle tea.PasteMsg so bracketed paste (Ctrl+V / Ctrl+Shift+V / right-click)
drops clipboard text into the focused composer; was silently dropped
- render the composer (in-session + launcher) borderless: top rule + flush text,
no side borders or trailing padding, so a terminal drag-copy yields just the
typed text instead of box chrome and whitespace
A multi-line paste put raw newlines into the single-line input slot, overflowing
the fixed-height box and leaving a smeared/stale region. flattenForDisplay collapses
newlines (↵) and tabs for rendering only; the inputBuffer keeps real characters for
submission.