Keep painting after cut (#13472)

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This can be enabled in Preference->Developer->Keep painted feature after
mesh change.

<img width="731" height="633" alt="init"
src="https://github.com/user-attachments/assets/8b195486-538e-4eda-9e77-bfdf1a794306"
/>


TODO:
- [ ] Bug fixes
- [ ] Make it faster
- Keep painting after other mesh operations such as reload from
disk/simplify/boolean operation etc:
  - [x] Planar cut
  - [x] Dovetail cut
  - [x] Cut with part assigned to other side
  - [x] Split to parts
  - [x] Split to objects
  - [x] Mesh boolean gizmo
  - [x] Mesh boolean in right click
- [x] Reload from disk/replace stl (won't work well if mesh changed too
much)
  - [x] Fix model
- [x] Simplify/smooth (this two won't work well due to too much mesh
changes)
- [x] Add options in settings since I think this will be experimental
for a long time until being tested by a lot of ppl

src/slic3r/GUI/Preferences.cpp

@@ -969,7 +969,7 @@ wxBoxSizer *PreferencesDialog::create_item_checkbox(wxString title, wxString too
             if (m_bambu_cloud_checkbox)      m_bambu_cloud_checkbox->Enable(!enabled);
         }
 
-        #ifdef __WXMSW__
+#ifdef __WXMSW__
         if (param == "associate_3mf") {
              bool pbool = app_config->get("associate_3mf") == "true" ? true : false;
              if (pbool) {
@@ -1853,6 +1853,9 @@ void PreferencesDialog::create_items()
     auto item_ams_blacklist    = create_item_checkbox(_L("Skip AMS blacklist check"), "", "skip_ams_blacklist_check");
     g_sizer->Add(item_ams_blacklist);
 
+    auto item_keep_painting    = create_item_checkbox(_L("(Experimental) Keep painted feature after mesh change"), _L("Attempt to keep painted features (color/seam/support/fuzzy etc.) after changing the object mesh (such as cut/reload from disk/simplify/fix etc.)\nHighly experimental! Slow and may create artifact."), "keep_painting");
+    g_sizer->Add(item_keep_painting);
+
     g_sizer->Add(create_item_title(_L("Storage")), 1, wxEXPAND);
     auto item_allow_abnormal_storage = create_item_checkbox(_L("Allow Abnormal Storage"), _L("This allows the use of Storage that is marked as abnormal by the Printer.\nUse at your own risk, can cause issues!"), "allow_abnormal_storage");
     g_sizer->Add(item_allow_abnormal_storage);