Stacked mode (<50 cols) now shows only the active pane (Local/Remote)
with a visual indicator bar. Tab switches between panes. Side-by-side
mode (>=50 cols) unchanged.
- NEW responsive.go: wrapFooter, adaptiveSidePad, clampWidth, truncateStr
- Footer auto-wraps to multi-line on narrow terminals (full labels preserved)
- Box width clamped to terminal width across all tabs
- Host/key/snippet rows truncated with ellipsis; compact format <35 cols
- SFTP panes stack vertically when terminal < 50 cols
- Tab bar truncates names on overflow
- Form contentW minimum lowered 50->30 for mobile
- Fixed: key_list_tab & snippet_list_tab dropped last data row (off-by-one bug)
swanadiva