feat: dual external spool support, AMS slot model filtering & pre-population

Backend:
- Add dual external spool support for H2D (vt_tray as list: Ext-L/Ext-R)
- Add cloud filament ID map endpoint (/cloud/filament-id-map)
- Fix RFID spool data erased by periodic AMS updates (skip tag matcher
  for RFID-tagged trays)
- Fix AMS slot config overwrites RFID spool state
- Fix K-profile selection corrupts existing profiles on X1C/P1S
- Resolve K-profiles filament name via cloud filament ID map
- Update print scheduler and usage tracker for dual external spools

Frontend:
- Add printer model filtering to ConfigureAmsSlotModal (cloud/local/builtin
  presets filtered by @BBL model suffix and compatible_printers)
- Add pre-population for configured slots (preset, color, K-profile)
- Add K-Profiles view with accurate filament name resolution
- Internationalize all ConfigureAmsSlotModal strings (en/de/fr/it/ja — 21 keys)
- Add 5 new ConfigureAmsSlotModal tests (model filtering, pre-selection,
  color pre-population, i18n)
- Update PrintersPage for dual external spool rendering

Docs:
- Update CHANGELOG, README, website features, and wiki AMS docs

backend/app/services/printer_manager.py

@@ -502,7 +502,7 @@ def printer_state_to_dict(state: PrinterState, printer_id: int | None = None, mo
     """
     # Parse AMS data from raw_data
     ams_units = []
-    vt_tray = None
+    vt_tray = []
     raw_data = state.raw_data or {}
 
     # Build K-profile lookup map: cali_idx -> k_value
@@ -578,37 +578,40 @@ def printer_state_to_dict(state: PrinterState, printer_id: int | None = None, mo
                 }
             )
 
-    # Parse virtual tray (external spool)
+    # Parse virtual tray (external spool) — now a list
     if "vt_tray" in raw_data:
-        vt_data = raw_data["vt_tray"]
-        vt_tag_uid = vt_data.get("tag_uid")
-        if vt_tag_uid in ("", "0000000000000000"):
-            vt_tag_uid = None
-        vt_tray_uuid = vt_data.get("tray_uuid")
-        if vt_tray_uuid in ("", "00000000000000000000000000000000"):
-            vt_tray_uuid = None
+        for vt_data in raw_data["vt_tray"]:
+            vt_tag_uid = vt_data.get("tag_uid")
+            if vt_tag_uid in ("", "0000000000000000"):
+                vt_tag_uid = None
+            vt_tray_uuid = vt_data.get("tray_uuid")
+            if vt_tray_uuid in ("", "00000000000000000000000000000000"):
+                vt_tray_uuid = None
 
-        # Get K value for vt_tray
-        vt_k_value = vt_data.get("k")
-        vt_cali_idx = vt_data.get("cali_idx")
-        if vt_k_value is None and vt_cali_idx is not None and vt_cali_idx in kprofile_map:
-            vt_k_value = kprofile_map[vt_cali_idx]
+            # Get K value for vt_tray
+            vt_k_value = vt_data.get("k")
+            vt_cali_idx = vt_data.get("cali_idx")
+            if vt_k_value is None and vt_cali_idx is not None and vt_cali_idx in kprofile_map:
+                vt_k_value = kprofile_map[vt_cali_idx]
 
-        vt_tray = {
-            "id": 254,
-            "tray_color": vt_data.get("tray_color"),
-            "tray_type": vt_data.get("tray_type"),
-            "tray_sub_brands": vt_data.get("tray_sub_brands"),
-            "tray_id_name": vt_data.get("tray_id_name"),
-            "tray_info_idx": vt_data.get("tray_info_idx"),
-            "remain": vt_data.get("remain", 0),
-            "k": vt_k_value,
-            "cali_idx": vt_cali_idx,
-            "tag_uid": vt_tag_uid,
-            "tray_uuid": vt_tray_uuid,
-            "nozzle_temp_min": vt_data.get("nozzle_temp_min"),
-            "nozzle_temp_max": vt_data.get("nozzle_temp_max"),
-        }
+            tray_id = int(vt_data.get("id", 254))
+            vt_tray.append(
+                {
+                    "id": tray_id,
+                    "tray_color": vt_data.get("tray_color"),
+                    "tray_type": vt_data.get("tray_type"),
+                    "tray_sub_brands": vt_data.get("tray_sub_brands"),
+                    "tray_id_name": vt_data.get("tray_id_name"),
+                    "tray_info_idx": vt_data.get("tray_info_idx"),
+                    "remain": vt_data.get("remain", 0),
+                    "k": vt_k_value,
+                    "cali_idx": vt_cali_idx,
+                    "tag_uid": vt_tag_uid,
+                    "tray_uuid": vt_tray_uuid,
+                    "nozzle_temp_min": vt_data.get("nozzle_temp_min"),
+                    "nozzle_temp_max": vt_data.get("nozzle_temp_max"),
+                }
+            )
 
     # Get ams_extruder_map from raw_data (populated by MQTT handler from AMS info field)
     ams_extruder_map = raw_data.get("ams_extruder_map", {})