Phase B — Tamagosh-inspired dual-pane file browser:
- Left pane: local filesystem (starts at /Users/swanadiva)
- Right pane: remote filesystem via SFTP
- Tab key switches active pane (green border = active)
- Local CWD indicator per pane
- File listing with dir/ file size display
- Filter mode with / key
- Copy files: C key copies from active pane to opposite pane
- Delete (D), mkdir (N on remote), Refresh (R)
- Esc to close
- File size formatting (B/KiB/MiB/GiB)
- Progress message during transfers
- StylePaneActive (green border) / StylePaneInactive (muted border)
- SFTPBrowserTab with remote directory browsing
- Open via Ctrl+F from host list
- Navigate dirs, filter with /, refresh with r
- Dir/icon display with file sizes
- Sort dirs first, then by name
swanadiva