v0.4.1: app filtering + clickable dashboard stat cards

Add filter bar (Mind/Futó/Leállítva/Telepíthető) to Alkalmazások page with
URL-based filter persistence. Dashboard stat cards are now clickable links
that navigate to the filtered stacks view.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

controller/internal/web/funcmap.go

@@ -144,5 +144,18 @@ func (s *Server) templateFuncMap() template.FuncMap {
 		"fmtLoad": func(load float64) string {
 			return fmt.Sprintf("%.2f", load)
 		},
+		"filterCategory": func(state stacks.ContainerState, deployed bool) string {
+			switch state {
+			case stacks.StateRunning, stacks.StateStarting, stacks.StateUnhealthy, stacks.StateRestarting:
+				return "running"
+			case stacks.StateStopped, stacks.StateExited, stacks.StatePaused:
+				return "stopped"
+			default:
+				if deployed {
+					return "stopped"
+				}
+				return "available"
+			}
+		},
 	}
 }