fix: prevent specific internal models from being overridden by preserve_external_surfaces

- Add !isSpecificInternal condition to user preferences check
- Ensure specific internal models maintain confidence=0.90 even when visible
- Fix issue where 12v4000g03_herhang.prt had confidence=0 despite being marked as internal

This ensures models explicitly marked as internal (like 12v4000g03_herhang.prt)
are always deletable regardless of their visibility or external surface preservation settings.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

CreoManager.cpp

@@ -1780,8 +1780,8 @@ CreoManager::ShellAnalysisResult CreoManager::AnalyzeShellFeaturesEnhanced(const
                     }
                 }
 
-                // Apply user preferences
-                if (request.preserve_external_surfaces && is_outer_component) {
+                // Apply user preferences (skip for specific internal models)
+                if (request.preserve_external_surfaces && is_outer_component && !isSpecificInternal) {
                     item.confidence = 0.0;  // Force keep
                 }