feat(webui): add health check monitoring for connection status

Implement periodic health checks every 15 seconds to monitor connection status,
pausing when the tab is hidden and resuming on visibility. Update UI bindings
to use data store for connection status instead of global store. Add destroy
method to clean up timers on component teardown.

public/js/data-store.js

@@ -16,6 +16,7 @@ document.addEventListener('alpine:init', () => {
         loading: false,
         connectionStatus: 'connecting',
         lastUpdated: '-',
+        healthCheckTimer: null,
 
         // Filters state
         filters: {
@@ -30,9 +31,8 @@ document.addEventListener('alpine:init', () => {
         // For simplicity, let's keep relevant filters here.
 
         init() {
-            // Watch filters to recompute
-            // Alpine stores don't have $watch automatically unless inside a component?
-            // We can manually call compute when filters change.
+            // Start health check monitoring
+            this.startHealthCheck();
         },
 
         async fetchData() {
@@ -63,11 +63,9 @@ document.addEventListener('alpine:init', () => {
 
                 this.computeQuotaRows();
 
-                this.connectionStatus = 'connected';
                 this.lastUpdated = new Date().toLocaleTimeString();
             } catch (error) {
                 console.error('Fetch error:', error);
-                this.connectionStatus = 'disconnected';
                 const store = Alpine.store('global');
                 store.showToast(store.t('connectionLost'), 'error');
             } finally {
@@ -75,6 +73,66 @@ document.addEventListener('alpine:init', () => {
             }
         },
 
+        async performHealthCheck() {
+            try {
+                // Get password from global store
+                const password = Alpine.store('global').webuiPassword;
+                
+                // Use lightweight health endpoint
+                const { response, newPassword } = await window.utils.request('/health', {}, password);
+                
+                if (newPassword) Alpine.store('global').webuiPassword = newPassword;
+                
+                if (response.ok) {
+                    this.connectionStatus = 'connected';
+                } else {
+                    this.connectionStatus = 'disconnected';
+                }
+            } catch (error) {
+                console.error('Health check error:', error);
+                this.connectionStatus = 'disconnected';
+            }
+        },
+
+        startHealthCheck() {
+            // Clear existing timer
+            if (this.healthCheckTimer) {
+                clearInterval(this.healthCheckTimer);
+            }
+
+            // Setup visibility change listener
+            if (!this._healthVisibilitySetup) {
+                this._healthVisibilitySetup = true;
+                document.addEventListener('visibilitychange', () => {
+                    if (document.hidden) {
+                        // Tab hidden - stop health checks
+                        this.stopHealthCheck();
+                    } else {
+                        // Tab visible - restart health checks
+                        this.startHealthCheck();
+                    }
+                });
+            }
+
+            // Perform immediate health check
+            this.performHealthCheck();
+
+            // Schedule regular health checks every 15 seconds
+            this.healthCheckTimer = setInterval(() => {
+                // Only perform health check if tab is visible
+                if (!document.hidden) {
+                    this.performHealthCheck();
+                }
+            }, 15000);
+        },
+
+        stopHealthCheck() {
+            if (this.healthCheckTimer) {
+                clearInterval(this.healthCheckTimer);
+                this.healthCheckTimer = null;
+            }
+        },
+
         computeQuotaRows() {
             const models = this.models || [];
             const rows = [];
@@ -209,6 +267,10 @@ document.addEventListener('alpine:init', () => {
             });
 
             return rows;
+        },
+
+        destroy() {
+            this.stopHealthCheck();
         }
     });
 });