feat: Filament Track Switch (H2-series O2L-FTS) support

The Filament Track Switch (H2-series accessory, product code O2L-FTS) feeds
every AMS to both extruders through a two-track switch. Port full support
across the device layer, project config, and GUI.

Device / config:
- Model the switch-aware AMS binding (the set of extruders an AMS can feed
  and which input track A/B feeds it), switch readiness, the O2L-FTS firmware
  module, and the fun2 capability bit for checking a slice against installed
  hardware.
- Register has_filament_switcher and enable_filament_dynamic_map as project
  config that persists with the project and restores from a saved 3mf, and
  force both back to false on every project/printer/CLI load path. Live
  device sync is the only thing that sets them true.

GUI:
- Sidebar sync activates the switch from live device state, attributes each
  AMS to the extruder its input track feeds, shows a floating status icon
  (ready / not-calibrated), and surfaces a one-time tip / not-calibrated
  warning.
- Send dialog gains a non-blocking slice-vs-hardware mismatch warning and a
  blocking error when a slice needs dynamic nozzle mapping but the switch is
  missing or not set up.
- AMS load/unload guards, AMS-view routing glyph + un-calibrated banner +
  hidden external-spool road, and mapping-popup external-spool lockout.
- Filament pickers collapse the per-extruder split into a single deduplicated
  "AMS filaments" group with a smart-assign toggle when the switch is ready.
- Firmware-upgrade panel lists the O2L-FTS accessory and its version.
- Device-provided filament-change steps (ams.cfs) drive the change-step
  display when firmware sends them, including the three switch steps.
- "Load current filament" asks which extruder to feed via a
  FeedDirectionDialog when the switch is calibrated.

Inert without the accessory: every path is gated on the switch being
installed (MQTT aux bit 29, default off) or ready, both project flags default
false, and the per-extruder AMS attribution is byte-identical, so AMS state,
the send/load UI, and sliced g-code are unchanged for every printer that does
not report a Filament Track Switch.

src/slic3r/GUI/DeviceManager.cpp

@@ -869,6 +869,7 @@ void MachineObject::clear_version_info()
     laser_version_info = DevFirmwareVersionInfo();
     cutting_module_version_info = DevFirmwareVersionInfo();
     extinguish_version_info = DevFirmwareVersionInfo();
+    filatrack_version_info = DevFirmwareVersionInfo();
     module_vers.clear();
     // Drop cached rack-hotend (WTM) firmware alongside the module list.
     // Inert for non-rack printers (rack firmware map is empty).
@@ -890,6 +891,8 @@ void MachineObject::store_version_info(const DevFirmwareVersionInfo& info)
         // the rack upgrade UI can read per-nozzle versions. isWTM() is false for every non-rack
         // printer's modules, so this branch never fires outside H2C.
         m_nozzle_system->AddFirmwareInfoWTM(info);
+    } else if (info.isFilaTrackSwitch()) {
+        filatrack_version_info = info;
     }
 
     module_vers.emplace(info.name, info);
@@ -1572,7 +1575,7 @@ int MachineObject::check_resume_condition()
     }
     return 0;
 }
-int MachineObject::command_ams_change_filament(bool load, std::string ams_id, std::string slot_id, int old_temp, int new_temp)
+int MachineObject::command_ams_change_filament(bool load, std::string ams_id, std::string slot_id, int old_temp, int new_temp, std::optional<int> extruder_id)
 {
     json j;
     try {
@@ -1604,6 +1607,13 @@ int MachineObject::command_ams_change_filament(bool load, std::string ams_id, st
             j["print"]["slot_id"] = atoi(slot_id.c_str());
         }
 
+        // Filament Track Switch: route the load to the chosen extruder. Only present when the
+        // caller supplied a value (FTS-installed+ready path), so every other caller is unchanged.
+        if (extruder_id.has_value())
+        {
+            j["print"]["extruder_id"] = *extruder_id;
+        }
+
     } catch (const std::exception &) {}
     return this->publish_json(j);
 }
@@ -5085,6 +5095,7 @@ void MachineObject::parse_new_info(json print)
     // fun2 may have infinite length, use get_flag_bits_no_border
     if (!fun2.empty()) {
         is_support_print_with_emmc = get_flag_bits_no_border(fun2, 0) == 1;
+        is_support_check_track_switch_match_slice_printer = get_flag_bits_no_border(fun2, 19) == 1;
     }
 
     /*aux*/