v1.19 — Bug fixes, Hungarian accents, better error handling

- Fix: Back button was always visible (ternary always returned Visible)
- Fix: Missing Hungarian accents on EditionPage ("Válasszon kiadást")
- Fix: Better ODT download error messages (network/timeout distinguished)
- Signed with Azure Trusted Signing (Microsoft root CA, instant SmartScreen trust)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Services/OdtDownloader.cs

@@ -85,6 +85,17 @@ namespace InstaSoftOfficeTool.Services
                 StatusChanged?.Invoke("ODT setup.exe k\u00e9sz.");
                 return true;
             }
+            catch (System.Net.Http.HttpRequestException ex)
+            {
+                StatusChanged?.Invoke("H\u00e1l\u00f3zati hiba: Nincs internetkapcsolat vagy a szerver nem el\u00e9rhet\u0151.");
+                StatusChanged?.Invoke("R\u00e9szletek: " + ex.Message);
+                return false;
+            }
+            catch (TaskCanceledException)
+            {
+                StatusChanged?.Invoke("Id\u0151t\u00fall\u00e9p\u00e9s: A let\u00f6lt\u00e9s t\u00fal sok\u00e1ig tartott. Ellen\u0151rizze az internetkapcsolatot.");
+                return false;
+            }
             catch (Exception ex)
             {
                 StatusChanged?.Invoke("Hiba: " + ex.GetType().Name + ": " + ex.Message);