Fix: Blazor Server loading screen now works correctly

Problem:
- Loading screen was getting stuck and not hiding properly
- Conflicting logic between pwa.js and inline scripts
- Blazor Server lifecycle not properly integrated with loading screen

Solution (Meziantou-inspired approach for Blazor Server):
1. **blazor-integration.js** - Now manages loading screen lifecycle:
   - Shows loading screen only on first load (sessionStorage check)
   - Hides screen when Blazor.start() promise resolves (SignalR connected)
   - Added reconnection UI for Blazor Server disconnections
   - Proper error handling if Blazor fails to start

2. **_Layout.cshtml** - Simplified loading screen management:
   - Removed inline script that was conflicting
   - Moved blazor-integration.js before pwa.js (load order critical)
   - Loading screen now controlled by Blazor lifecycle

3. **pwa.js** - Removed conflicting logic:
   - Removed hideLoadingScreen() method
   - Removed 5-second fallback timeout
   - PWA initialization no longer interferes with Blazor loading

Key Differences from WebAssembly Approach:
- WASM: Downloads .NET runtime + shows download progress
- Server: Establishes SignalR connection + shows spinner
- Loading screen hides when SignalR connection is ready

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

LittleShop/wwwroot/js/pwa.js

@@ -39,22 +39,9 @@ class PWAManager {
         // Setup push notifications
         this.setupPushNotifications();
 
-        // Hide loading screen after initialization
-        this.hideLoadingScreen();
-    }
-
-    hideLoadingScreen() {
-        const loadingScreen = document.getElementById('pwa-loading-screen');
-        if (loadingScreen && loadingScreen.style.display !== 'none') {
-            // Add fade-out class
-            loadingScreen.classList.add('fade-out');
-
-            // Hide after animation completes (don't remove from DOM to avoid layout issues)
-            setTimeout(() => {
-                loadingScreen.style.display = 'none';
-                console.log('PWA: Loading screen hidden');
-            }, 500);
-        }
+        // Loading screen is now managed by blazor-integration.js
+        // Don't interfere with Blazor Server's loading lifecycle
+        console.log('PWA: Initialization complete (loading screen managed by Blazor)');
     }
 
     setupInstallPrompt() {
@@ -701,15 +688,5 @@ window.addEventListener('load', () => {
     }
 });
 
-// Fallback: Ensure loading screen is hidden after maximum timeout
-// This guarantees the loading screen won't stay visible indefinitely
-setTimeout(() => {
-    const loadingScreen = document.getElementById('pwa-loading-screen');
-    if (loadingScreen && loadingScreen.style.display !== 'none') {
-        console.log('PWA: Hiding loading screen via fallback timeout');
-        loadingScreen.classList.add('fade-out');
-        setTimeout(() => {
-            loadingScreen.style.display = 'none';
-        }, 500);
-    }
-}, 5000); // 5 second maximum
+// Loading screen fallback timeout removed - now managed by blazor-integration.js
+// Blazor Server controls loading screen lifecycle based on SignalR connection state