feat: refactor health check endpoint with real-time worker status

Extract health check logic into GetHealth method on Config struct and
integrate with Worker service for accurate scan status reporting.

Changes:
- Move health check handler from inline function to Config.GetHealth()
- Add Worker field to Config struct for dependency injection
- Wire Worker into main server dependencies
- Report actual scan_in_progress status using Worker.HasActiveScans()
- Report actual active_jobs count using Worker.GetActiveJobCount()

This provides more accurate health monitoring by checking the real state
of background jobs rather than returning static placeholder values.

cmd/server/main.go

@@ -175,6 +175,7 @@ func main() {
 		DashboardHandler:      dashboardHandler,
 		DashboardService:      dashboardService,
 		OPDSHandler:           opdsHandler,
+		Worker:                worker,
 		SystemSettingsHandler: systemSettingsHandler,
 		ConnManager:           connManager,
 		QueueProcessor:        queueProcessor,

internal/router/frontend.go

@@ -825,28 +825,30 @@ func registerFrontendRoutes(cfg *Config) {
 		return c.HTML(http.StatusOK, buf.String())
 	})
 
-	// ============================================================================
+	e.GET("/health", cfg.GetHealth)
-	// HEALTH CHECK
+}
-	// ============================================================================
 
-	// Health check
+// ============================================================================
-	e.GET("/health", func(c echo.Context) error {
+// HEALTH CHECK
+// ============================================================================
+
+// Health check
+func (cfg *Config) GetHealth(c echo.Context) error {
 	ctx, cancel := context.WithTimeout(c.Request().Context(), 2*time.Second)
 	defer cancel()
-
 	if err := pingDB(cfg, ctx); err != nil {
 		return c.JSON(http.StatusServiceUnavailable, map[string]string{
 			"status": "unhealthy",
 			"error":  err.Error(),
 		})
 	}
+
 	return c.JSON(http.StatusOK, map[string]interface{}{
 		"status":   "healthy",
 		"database": "connected",
 		"scan": map[string]interface{}{
-				"scan_in_progress": false, // Would check worker results
+			"scan_in_progress": cfg.Worker.HasActiveScans(),
-				"active_jobs":      0,     // Would count running jobs
+			"active_jobs":      cfg.Worker.GetActiveJobCount(),
 		},
 	})
-	})
 }

internal/router/router.go

@@ -52,6 +52,7 @@ type Config struct {
 	AnalyticsHandler      *handlers.AnalyticsHandler
 	QueueHandler          *handlers.QueueHandler
 	CollectionHandler     *handlers.CollectionHandler
+	Worker                *services.Worker
 	DashboardHandler      *handlers.DashboardHandler
 	DashboardService      *services.DashboardService
 	OPDSHandler           *handlers.OPDSHandler