Implement complete keyboard navigation and UI enhancement

Phase 1 - Panel Navigation:
- Add PanelType enum and panel focus state management
- Implement Shift+Tab cycling between panels (System → Services → Backup → Network)
- Add visual focus indicators with blue borders for focused panels
- Preserve existing Tab behavior for host switching

Phase 2 - Dynamic Statusbar:
- Add bottom statusbar with context-aware shortcuts
- Display different shortcuts based on focused panel
- Global shortcuts: Tab, Shift+Tab, Up/Down arrows, Q
- Panel-specific shortcuts: R (Rebuild), Space/R (Services), B (Backup), N (Network)

Phase 3 - Scrolling Support:
- Add scroll state management per host and panel type
- Implement Up/Down arrow key scrolling within focused panels
- Smart scrolling that activates only when content exceeds panel height
- Scroll bounds checking to prevent over-scrolling

Complete keyboard navigation experience with visual feedback and contextual help.

CLAUDE.md

@@ -40,20 +40,35 @@ Storage:
  └─ ● 18% 167.4GB/928.2GB
 ```
 
-**Outstanding Issue:**
-- Dashboard displays "Build: unknown" despite agent collecting metrics correctly
-- Need to investigate ZMQ communication or dashboard metric filtering
+**Current Status - October 23, 2025:**
+- System panel layout fully implemented with blue tree symbols ✅
+- Backup panel layout restructured per specification ✅  
+- Tree symbols now use consistent blue theming across all panels ✅
+- Overflow handling restored for all widgets ("... and X more") ✅
+- Agent hash display working correctly ✅
 
-### Future Priorities
+### Next Implementation Phase: Keyboard Navigation & UI Enhancement
 
-**Keyboard Navigation (Dashboard):**
-- Change host switching to "Shift-Tab"
-- Add panel navigation with "Tab"
-- Add scrolling support for overflow content
+**Phase 1 - Panel Navigation (In Progress):**
+- Add panel focus state management to TuiApp
+- Implement Shift-Tab for panel cycling (System → Services → Backup → Network)
+- Keep Tab for host switching as current behavior
+- Add visual focus indicators to panel borders
 
-**Remote Execution (Agent/Dashboard):**
-- Dynamic statusbar with context shortcuts
-- Remote nixos rebuild commands
+**Phase 2 - Dynamic Statusbar:**
+- Create bottom statusbar showing context-aware shortcuts
+- System panel: "R: Rebuild", "S: Services" 
+- Services panel: "Space: Start/Stop", "R: Restart"
+- Backup panel: "B: Trigger Backup"
+- Global: "Tab: Switch Host", "Shift-Tab: Switch Panel"
+
+**Phase 3 - Scrolling Support:**
+- Add Up/Down arrow key handling within focused panels
+- Implement scroll offset tracking for overflow content
+- Add scroll position indicators (↑/↓) when needed
+
+**Future - Remote Execution:**
+- Remote nixos rebuild commands via dashboard
 - Service start/stop/restart controls
 - Backup trigger functionality