fix(editor): Create + Generate button now actually runs generation pipeline

- "Create + Generate" was setting a flag but never calling generateCompleteZone()
- Now properly chains: create terrain → run full procedural pipeline
  (noise → smooth → normals → height paint → slope paint → detail → water → beaches)
- Uses generateAfterCreate_ flag to defer generation until after terrain is created

tools/editor/editor_ui.hpp

@@ -44,6 +44,7 @@ private:
     bool showSaveDialog_ = false;
     bool showHelp_ = false;
     bool showAbout_ = false;
+    bool generateAfterCreate_ = false;
 
     char newMapNameBuf_[256] = "CustomZone";
     int newTileX_ = 32;