Simplify navigation and add vi-style keys

Major UI simplification and navigation improvements:

Changes:
- Removed panel selection concept entirely (no more Shift+Tab)
- Service selection always visible with blue highlighting
- Up/Down arrows now directly control service selection
- Added j/k vi-style navigation keys as alternatives to arrow keys
- Removed panel focus borders - all panels look uniform
- Service commands (s/S) work without panel focus requirements
- Updated keyboard shortcuts to reflect simplified navigation

Navigation:
- Tab: Switch hosts
- ↑↓/jk: Select service (always works)
- R: Rebuild host
- s: Start service
- S: Stop service
- q: Quit

The interface is now much simpler and more intuitive with direct service control.

dashboard/src/ui/widgets/services.rs

@@ -443,11 +443,7 @@ impl ServicesWidget {
 
     /// Render with focus, scroll, and pending transitions for visual feedback
     pub fn render_with_transitions(&mut self, frame: &mut Frame, area: Rect, is_focused: bool, scroll_offset: usize, pending_transitions: &HashMap<String, (CommandType, String, std::time::Instant)>) {
-        let services_block = if is_focused {
-            Components::focused_widget_block("services")
-        } else {
-            Components::widget_block("services")
-        };
+        let services_block = Components::widget_block("services");
         let inner_area = services_block.inner(area);
         frame.render_widget(services_block, area);