Raft, support interface fix and overhaul (#10947)

* Support interface fix

* Tree support true interlace

* remove pure format changes

---------

Co-authored-by: SoftFever <softfeverever@gmail.com>

src/libslic3r/Support/TreeSupport.hpp

@@ -459,6 +459,21 @@ private:
      * \param contact_nodes The nodes to draw as support.
      */
     void draw_circles();
+    
+    /*!
+     * \brief Normalize interface IDs for interlaced supports.
+     *
+     * Reassigns sequential IDs to support layers when using
+     * RectilinearInterlaced, alternating (0,1,0,1,…) so consecutive
+     * interface layers never share orientation. Applies to all support
+     * area groups, including transition layers (e.g. TreeStrong
+     * body-to-interface), as well as top and bottom interfaces, so
+     * FillRectilinearInterlaced computes correct extrusion angles.
+     *
+     * \note Call after support layers are built and before toolpaths,
+     * so fillers use the normalized IDs.
+     */
+    void normalize_interface_ids();
 
     /*!
      * \brief Drops down the nodes of the tree support towards the build plate.