Add choices API endpoint and OpenAPI client setup

Introduces a new /api/choices/ endpoint for fetching model choices with multilingual labels. Updates Django models to use 'cz#' prefix for Czech labels. Adds OpenAPI client generation via orval, refactors frontend API structure, and provides documentation and helper scripts for dynamic choices and OpenAPI usage.

backend/vontor_cz/urls.py

@@ -16,6 +16,7 @@ Including another URLconf
 """
 from django.contrib import admin
 from django.urls import path, include
+from .views import choices
 
 from drf_spectacular.views import (
     SpectacularAPIView,
@@ -31,6 +32,7 @@ urlpatterns = [
 
 
     path('admin/', admin.site.urls),
+    path("api/choices/", choices, name="choices"),
     path('api/account/', include('account.urls')),
     path('api/commerce/', include('commerce.urls')),
     #path('api/advertisments/', include('advertisements.urls')),

backend/vontor_cz/views.py

@@ -0,0 +1,85 @@
+import json
+from django.apps import apps
+from rest_framework.decorators import api_view
+from rest_framework.response import Response
+from drf_spectacular.utils import extend_schema, OpenApiParameter
+from rest_framework.permissions import AllowAny
+
+@extend_schema(
+    description="Vrátí všechny možné hodnoty pro ChoiceField s podporou vícejazyčných labelů. "
+                "Umožňuje načíst více modelů a polí najednou.",
+    parameters=[
+        OpenApiParameter(
+            name="fields",
+            description=(
+                "JSON pole objektů {model: 'ModelName', field: 'field_name'} "
+                "např. '[{\"model\": \"User\", \"field\": \"role\"}, {\"model\": \"Carrier\", \"field\": \"shipping_method\"}]'"
+            ),
+            required=True,
+            type=str,
+        ),
+        OpenApiParameter(
+            name="lang",
+            description="Jazyk pro labely (např. 'cz', 'en')",
+            required=False,
+            type=str,
+        ),
+    ],
+    responses={
+        200: {
+            "type": "object",
+            "additionalProperties": {
+                "type": "array",
+                "items": {
+                    "type": "object",
+                    "properties": {
+                        "value": {"type": "string", "description": "Logická hodnota pro backend"},
+                        "label": {"type": "string", "description": "Human-readable label podle zvoleného jazyka"}
+                    }
+                }
+            }
+        }
+    }
+)
+@api_view(["GET"])
+def choices(request):
+    """
+    Endpoint pro získání choices pro dropdowny s podporou vícejazyčných labelů.
+    Formát labelu v modelu: 'lang#Label', např. 'cz#Administrátor'.
+    Podporuje více modelů a polí najednou.
+    """
+    permission_classes = [AllowAny]
+
+    fields_param = request.query_params.get("fields")
+    lang = request.query_params.get("lang", None)
+
+    try:
+        fields_list = json.loads(fields_param)
+    except Exception:
+        return Response({"error": "Invalid 'fields' parameter, must be valid JSON"}, status=400)
+
+    result = {}
+    for item in fields_list:
+        model_name = item.get("model")
+        field_name = item.get("field")
+        if not model_name or not field_name:
+            continue
+
+        model = apps.get_model("app_name", model_name)
+        field = model._meta.get_field(field_name)
+
+        choices_data = []
+        for value, label in field.choices:
+            if "#" in label and lang:
+                label_parts = label.split("#", 1)
+                if label_parts[0] == lang:
+                    label = label_parts[1]
+                else:
+                    label = label_parts[1]  # fallback na defaultní text (po #)
+            elif "#" in label:
+                label = label.split("#", 1)[1]
+            choices_data.append({"value": value, "label": label})
+
+        result[f"{model_name}.{field_name}"] = choices_data
+
+    return Response(result)