docs: add responsive layout plan to PROJECT_STATE.md and CHANGELOG.md

CHANGELOG.md

@@ -16,6 +16,16 @@
 - **sftp_browser_tab.go footer**: Added `Enter/→:open`, `←/Backspace:up`
 - **form tabs footer**: Added `Shift+Tab:prev`, `↑↓:nav`
 
+### Responsive Layout (In Progress)
+- **NEW `responsive.go`**: Shared helpers (`wrapFooter`, `adaptiveSidePad`, `clampWidth`, `truncateStr`)
+- Footer auto-wraps to multi-line when terminal is narrow (full labels preserved)
+- Box width clamped to terminal width — no more overflow
+- Host/key/snippet rows truncated with `…` when names are too long
+- SFTP panes stack vertically when terminal < 50 cols
+- Tab bar truncates tab names on overflow
+- Form contentW minimum lowered to 30 for mobile (Termux)
+- Breakpoints: compact (<60), medium (60–100), wide (≥100)
+
 ## v1.0.0 (2025-01-30)
 
 ### Added