feat: Phase 7 — MeshCentral Remote Desktop Integration

Backend:
- MeshCentralOptions + MeshCentralService: Node-Lookup via Hostname, Remote-Desktop-URL-Generierung
- RemoteDesktopController: GET /api/v1/agents/{id}/remote-session mit 3 Status-Zuständen (nicht konfiguriert / Agent fehlt / bereit)
- Program.cs: HttpClient + MeshCentralService registriert, appsettings.json mit Konfigurationsblock

Go Agent:
- config.go: MeshCentralUrl + MeshEnabled Felder
- internal/meshagent/installer.go: MeshAgent Download + Installation (Windows Service / Linux systemd)
- main.go: Automatische MeshAgent-Installation nach Enrollment wenn aktiviert

Frontend:
- RemoteDesktopButton: Modales Dialog mit 3 Zustandsanzeigen (Setup nötig / Agent installieren / Remote Desktop öffnen)
- AgentDetailPage: RemoteDesktopButton im Header integriert
- api/types.ts + api/client.ts: RemoteSessionInfo Typ + remoteDesktopApi

docker-compose.yml: MeshCentral Service (ghcr.io/ylianst/meshcentral:latest, Ports 4430/4431)

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

Backend/src/NexusRMM.Infrastructure/Migrations/RmmDbContextModelSnapshot.cs

@@ -74,7 +74,7 @@ namespace NexusRMM.Infrastructure.Migrations
 
                     b.HasIndex("MacAddress");
 
-                    b.ToTable("Agents");
+                    b.ToTable("Agents", (string)null);
                 });
 
             modelBuilder.Entity("NexusRMM.Core.Models.AgentMetric", b =>
@@ -100,7 +100,7 @@ namespace NexusRMM.Infrastructure.Migrations
 
                     b.HasIndex("Timestamp");
 
-                    b.ToTable("AgentMetrics");
+                    b.ToTable("AgentMetrics", (string)null);
                 });
 
             modelBuilder.Entity("NexusRMM.Core.Models.Alert", b =>
@@ -138,7 +138,7 @@ namespace NexusRMM.Infrastructure.Migrations
 
                     b.HasIndex("RuleId");
 
-                    b.ToTable("Alerts");
+                    b.ToTable("Alerts", (string)null);
                 });
 
             modelBuilder.Entity("NexusRMM.Core.Models.AlertRule", b =>
@@ -172,7 +172,7 @@ namespace NexusRMM.Infrastructure.Migrations
 
                     b.HasKey("Id");
 
-                    b.ToTable("AlertRules");
+                    b.ToTable("AlertRules", (string)null);
                 });
 
             modelBuilder.Entity("NexusRMM.Core.Models.SoftwarePackage", b =>
@@ -219,7 +219,7 @@ namespace NexusRMM.Infrastructure.Migrations
                     b.HasIndex("Name", "Version", "OsType")
                         .IsUnique();
 
-                    b.ToTable("SoftwarePackages");
+                    b.ToTable("SoftwarePackages", (string)null);
                 });
 
             modelBuilder.Entity("NexusRMM.Core.Models.TaskItem", b =>
@@ -253,7 +253,7 @@ namespace NexusRMM.Infrastructure.Migrations
 
                     b.HasIndex("AgentId");
 
-                    b.ToTable("Tasks");
+                    b.ToTable("Tasks", (string)null);
                 });
 
             modelBuilder.Entity("NexusRMM.Core.Models.Ticket", b =>
@@ -291,7 +291,7 @@ namespace NexusRMM.Infrastructure.Migrations
 
                     b.HasIndex("AgentId");
 
-                    b.ToTable("Tickets");
+                    b.ToTable("Tickets", (string)null);
                 });
 
             modelBuilder.Entity("NexusRMM.Core.Models.AgentMetric", b =>