Implements save/load/delete functionality for focus mode pin configurations:
**TUI Changes:**
- [ key to save current focus configuration as named preset
- ] key to cycle through saved presets
- Preset commands in CommandPalette (Ctrl+K):
- preset:save - Save current focus
- preset:list - List all presets
- preset:load:<name> - Load a specific preset
- preset:delete:<name> - Delete a preset
- Presets stored in ~/.fabric/focus-presets.json
- Updated help text with new keybindings
**Web Changes:**
- Preset dropdown in header with save/load/delete UI
- Modal dialog for saving new presets
- Presets stored in localStorage
- Styled with CSS matching existing UI
**Core:**
- FocusPresetManager utility class for preset CRUD operations
- Storage abstraction (Memory, LocalStorage, File-based)
- Full test coverage for preset management
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude Worker <noreply@anthropic.com>
