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/DeviceCore/DevDefs.h

@@ -41,6 +41,31 @@ enum AmsStatusMain
     AMS_STATUS_MAIN_UNKNOWN = 0xFF,
 };
 
+// Device-numbered filament-change step codes. Newer firmware reports the exact change-step
+// sequence through the AMS (ams.cfs), keyed by these codes, instead of the client hardcoding
+// steps per model. Distinct from the legacy GUI-side Slic3r::GUI::FilamentStep enum.
+// STEP_CHECK_POSITION and STEP_CONFIRM_EXTRUDED share code 0x08 by device design.
+enum DevFilamentStep
+{
+    STEP_IDLE = 0x00,
+    STEP_PAUSE = 0x01,
+    STEP_HEAT_NOZZLE = 0x02,
+    STEP_CUT_FILAMENT = 0x03,
+    STEP_PULL_CURR_FILAMENT = 0x04,
+    STEP_PUSH_NEW_FILAMENT = 0x05,
+    STEP_GRAB_NEW_FILAMENT = 0x06,
+    STEP_PURGE_OLD_FILAMENT = 0x07,
+    STEP_CHECK_POSITION = 0x08,
+    STEP_SWITCH_EXTRUDER = 0x09,
+    STEP_SWITCH_HOTEND = 0x0A,
+    STEP_AMS_FILA_COOLING = 0x0B,
+    STEP_PUSH_SWITCHER_FILA = 0x0C,
+    STEP_PULL_SWITCHER_FILA = 0x0D,
+    STEP_SWITCHER_SWITCH = 0x0E,
+    STEP_CONFIRM_EXTRUDED = 0x08,
+    STEP_COUNT,
+};
+
 // Slots and Tray
 #define VIRTUAL_TRAY_MAIN_ID    255
 #define VIRTUAL_TRAY_DEPUTY_ID  254