Address code review: improve exception handling with specific catch blocks

Co-authored-by: JusterZhu <11714536+JusterZhu@users.noreply.github.com>

Author: Copilot

src/c#/GeneralUpdate.Common/Shared/Object/ConfiginfoBuilder.cs

@@ -135,9 +135,24 @@ private static ConfiginfoBuilder LoadFromConfigFile()
 
                 return builder;
             }
+            catch (System.Text.Json.JsonException)
+            {
+                // Invalid JSON format, fall back to parameters
+                return null;
+            }
+            catch (IOException)
+            {
+                // File read error, fall back to parameters
+                return null;
+            }
+            catch (UnauthorizedAccessException)
+            {
+                // Permission denied, fall back to parameters
+                return null;
+            }
             catch
             {
-                // If there's any error reading or parsing the file, return null
+                // Any other unexpected error, fall back to parameters
                 return null;
             }
         }
@@ -184,6 +199,8 @@ private void InitializePlatformDefaults()
             _skipDirectorys = new List<string>();
 
             // Set default InstallPath to current program running directory
+            // This is set here to ensure the builder has a consistent default
+            // even though BaseConfigInfo also has this default via property initializer
             _installPath = AppDomain.CurrentDomain.BaseDirectory;
         }