Fix Client Performance Retry button not re-detecting IP (#597)

* Fix mobile nav bar getting stuck hidden on state change and client retry on IP change

- Add ResizeObserver to force-show nav bar when content shrinks below scrollable
- Change Client Performance Retry button to full page reload so HttpContext re-detects IP

* Fix nav bar stuck hidden at top of page - clear auto-hide timer instead of starting it

At scrollTop=0, the bar would show then auto-hide after 2s with no way to
scroll further up to recover it. Now clears the timer so the bar stays visible
at the top of the page.

* Preserve initial auto-hide but prevent stuck nav on scroll-back-to-top

Track hasScrolledDown flag so auto-hide at scrollTop=0 only fires on
initial page load. Once the user scrolls down and back up, they're
reaching for the nav - keep it visible. Reset flag on navigation.

* Only set hasScrolledDown on real scroll-down hide, not on layout-shift events

* Revert nav bar auto-hide changes - was a Blazor connection issue, not a scroll bug

* Add Retry button to Device Offline banner

Author: tvancott42

src/NetworkOptimizer.Web/Components/Pages/ClientDashboard.razor

@@ -90,6 +90,7 @@
                     <strong>Device Offline</strong>
                     <span>This device is currently offline. Showing historical data. Live data will appear when it reconnects.</span>
                 </div>
+                <button class="btn btn-primary btn-sm" @onclick="() => NavigationManager.NavigateTo(NavigationManager.Uri, forceLoad: true)">Retry</button>
             </div>
         </div>
     }
@@ -122,7 +123,7 @@
         <div class="card empty-state">
             <h3>Device Not Found</h3>
             <p>Could not identify your device on the network. Make sure you're connected and the UniFi Console is reachable.</p>
-            <button class="btn btn-primary" @onclick="RetryIdentify">Retry</button>
+            <button class="btn btn-primary" @onclick="() => NavigationManager.NavigateTo(NavigationManager.Uri, forceLoad: true)">Retry</button>
         </div>
     }
     else
@@ -1638,12 +1639,6 @@
         return (from, to);
     }
 
-    private async Task RetryIdentify()
-    {
-        await IdentifyAndLoadAsync();
-        StateHasChanged();
-    }
-
     private void ToggleResultExpand(int resultId)
     {
         _expandedResultId = _expandedResultId == resultId ? null : resultId;