fix(editor): object ID reset on load, zone name validation

- ObjectPlacer::loadFromFile() now resets uniqueIdCounter_ and clears
  selectedIndices_ to prevent ID collisions on repeated loads
- Zone rename validates against path traversal and special characters
  (rejects slashes, dots, colons, control chars, empty strings)
- UI shows error toast for invalid zone names

tools/editor/editor_app.hpp

@@ -54,7 +54,16 @@ public:
     QuestEditor& getQuestEditor() { return questEditor_; }
     AssetBrowser& getAssetBrowser() { return assetBrowser_; }
     EditorViewport& getViewport() { return viewport_; }
-    void setMapName(const std::string& name) { loadedMap_ = name; }
+    bool setMapName(const std::string& name) {
+        if (name.empty()) return false;
+        for (char c : name) {
+            if (c == '/' || c == '\\' || c == '.' || c == ':' ||
+                c == '*' || c == '?' || c == '"' || c == '<' ||
+                c == '>' || c == '|' || c < 32) return false;
+        }
+        loadedMap_ = name;
+        return true;
+    }
     rendering::TerrainRenderer* getTerrainRenderer();
     rendering::M2Renderer* getM2Renderer() { return viewport_.getM2Renderer(); }
     pipeline::AssetManager* getAssetManager() { return assetManager_.get(); }

tools/editor/editor_ui.cpp

@@ -2254,8 +2254,10 @@ void EditorUI::renderPropertiesPanel(EditorApp& app) {
             ImGui::SetNextItemWidth(140);
             if (ImGui::InputText("##mapname", renameBuf, sizeof(renameBuf),
                     ImGuiInputTextFlags_EnterReturnsTrue)) {
-                app.setMapName(renameBuf);
-                app.showToast("Zone renamed: " + std::string(renameBuf));
+                if (app.setMapName(renameBuf))
+                    app.showToast("Zone renamed: " + std::string(renameBuf));
+                else
+                    app.showToast("Invalid name (no slashes or special chars)");
             }
             ImGui::SameLine();
             ImGui::Text("[%d, %d]", app.getLoadedTileX(), app.getLoadedTileY());

tools/editor/object_placer.cpp

@@ -244,6 +244,8 @@ bool ObjectPlacer::loadFromFile(const std::string& path) {
         objects_.clear();
         undoStack_.clear();
         selectedIdx_ = -1;
+        selectedIndices_.clear();
+        uniqueIdCounter_ = 1;
 
         for (const auto& jo : arr) {
             PlacedObject obj;