Merge branch 'main' into feat/plugin-feature

Resolve five conflicts, all of which needed both sides rather than a pick:

- BackgroundSlicingProcess: ours was a pure tabs->spaces reformat of base, so
  keep main's per-filament volume/nozzle map read-back (its only change here).
- GUI_App: main's #12506 else-if attached to an `if` this branch deleted;
  re-expressed onto the same-agent early-return path (the agent factory caches
  per id, so pointer equality is the same predicate).
- MainFrame: both sides relocated Sync Presets independently; keep main's
  push_notification plus the branch's Plugins menu items.
- Tab: the "TODO: Orca: Support hybrid" blocks were unchanged base, not a branch
  decision; take main's enabled Hybrid to match the already auto-merged siblings.
- test_config: union of both sides' cases (6 plugin + 9 multi-nozzle).

src/slic3r/GUI/Tab.hpp

@@ -609,6 +609,8 @@ public:
     void        clear_pages() override;
 	bool 		supports_printer_technology(const PrinterTechnology tech) const override { return tech == ptFFF; }
 
+	void		on_value_change(const std::string& opt_key, const boost::any& value) override;
+
     const std::string&	get_custom_gcode(const t_config_option_key& opt_key) override;
     void				set_custom_gcode(const t_config_option_key& opt_key, const std::string& value) override;
 };
@@ -667,11 +669,11 @@ public:
 	bool 		supports_printer_technology(const PrinterTechnology /* tech */) const override { return true; }
 
 	void		set_extruder_volume_type(int extruder_id, NozzleVolumeType type);
+	void		on_value_change(const std::string& opt_key, const boost::any& value) override;
 
 	wxSizer*	create_bed_shape_widget(wxWindow* parent);
 	void		cache_extruder_cnt(const DynamicPrintConfig* config = nullptr);
 	bool		apply_extruder_cnt_from_cache();
-
 };
 
 class TabSLAMaterial : public Tab