Fix host navigation to work with alphabetical host ordering

- Fix host_index calculation for localhost to use actual position in sorted list
- Remove incorrect assumption that localhost is always at index 0
- Host navigation (Tab key) now works correctly with all hosts in alphabetical order

Fixes issue where only 3 of 5 hosts were accessible via Tab navigation.

dashboard/src/ui/mod.rs

@@ -146,8 +146,9 @@ impl TuiApp {
         if !self.available_hosts.is_empty() {
             if self.available_hosts.contains(&localhost) && !self.user_navigated_away {
                 // Localhost is available and user hasn't navigated away - switch to it
-                self.current_host = Some(localhost);
-                self.host_index = 0; // localhost is always first in sorted_hosts
+                self.current_host = Some(localhost.clone());
+                // Find the actual index of localhost in the sorted list
+                self.host_index = self.available_hosts.iter().position(|h| h == &localhost).unwrap_or(0);
             } else if self.current_host.is_none() {
                 // No current host - select first available (which is localhost if available)
                 self.current_host = Some(self.available_hosts[0].clone());