feat: add vehicle type assignment to vehicle edit/create form

frontend/src/pages/FahrzeugForm.tsx

@@ -1,8 +1,10 @@
 import React, { useEffect, useState, useCallback } from 'react';
 import {
   Alert,
+  Autocomplete,
   Box,
   Button,
+  Chip,
   CircularProgress,
   Container,
   Grid,
@@ -15,6 +17,8 @@ import { useNavigate, useParams } from 'react-router-dom';
 import DashboardLayout from '../components/dashboard/DashboardLayout';
 import GermanDateField from '../components/shared/GermanDateField';
 import { vehiclesApi } from '../services/vehicles';
+import { fahrzeugTypenApi } from '../services/fahrzeugTypen';
+import type { FahrzeugTyp } from '../types/checklist.types';
 import {
   CreateFahrzeugPayload,
   UpdateFahrzeugPayload,
@@ -78,12 +82,22 @@ function FahrzeugForm() {
   const [saveError, setSaveError] = useState<string | null>(null);
   const [fieldErrors, setFieldErrors] = useState<Partial<Record<keyof FormState, string>>>({});
 
+  const [allTypes, setAllTypes]         = useState<FahrzeugTyp[]>([]);
+  const [selectedTypes, setSelectedTypes] = useState<FahrzeugTyp[]>([]);
+
+  useEffect(() => {
+    fahrzeugTypenApi.getAll().then(setAllTypes).catch(() => {});
+  }, []);
+
   const fetchVehicle = useCallback(async () => {
     if (!id) return;
     try {
       setLoading(true);
       setError(null);
-      const vehicle = await vehiclesApi.getById(id);
+      const [vehicle, types] = await Promise.all([
+        vehiclesApi.getById(id),
+        fahrzeugTypenApi.getTypesForVehicle(id).catch(() => [] as FahrzeugTyp[]),
+      ]);
       setForm({
         bezeichnung:            vehicle.bezeichnung,
         kurzname:               vehicle.kurzname ?? '',
@@ -98,6 +112,7 @@ function FahrzeugForm() {
         paragraph57a_faellig_am: toDateInput(vehicle.paragraph57a_faellig_am),
         naechste_wartung_am:    toDateInput(vehicle.naechste_wartung_am),
       });
+      setSelectedTypes(types);
     } catch {
       setError('Fahrzeug konnte nicht geladen werden.');
     } finally {
@@ -162,6 +177,7 @@ function FahrzeugForm() {
           naechste_wartung_am:    form.naechste_wartung_am || null,
         };
         await vehiclesApi.update(id, payload);
+        await fahrzeugTypenApi.setTypesForVehicle(id, selectedTypes.map((t) => t.id));
         navigate(`/fahrzeuge/${id}`);
       } else {
         const payload: CreateFahrzeugPayload = {
@@ -179,6 +195,7 @@ function FahrzeugForm() {
           naechste_wartung_am:    form.naechste_wartung_am || undefined,
         };
         const newVehicle = await vehiclesApi.create(payload);
+        await fahrzeugTypenApi.setTypesForVehicle(newVehicle.id, selectedTypes.map((t) => t.id));
         navigate(`/fahrzeuge/${newVehicle.id}`);
       }
     } catch {
@@ -268,6 +285,24 @@ function FahrzeugForm() {
                 placeholder="z.B. WN-FW 1"
               />
             </Grid>
+            <Grid item xs={12}>
+              <Autocomplete
+                multiple
+                options={allTypes}
+                getOptionLabel={(o) => o.name}
+                value={selectedTypes}
+                onChange={(_e, val) => setSelectedTypes(val)}
+                isOptionEqualToValue={(a, b) => a.id === b.id}
+                renderTags={(value, getTagProps) =>
+                  value.map((option, index) => (
+                    <Chip label={option.name} size="small" {...getTagProps({ index })} key={option.id} />
+                  ))
+                }
+                renderInput={(params) => (
+                  <TextField {...params} label="Fahrzeugtypen" placeholder={selectedTypes.length === 0 ? 'Typen auswählen…' : ''} />
+                )}
+              />
+            </Grid>
           </Grid>
 
           <Typography variant="h6" gutterBottom sx={{ mt: 3 }}>Prüf- und Wartungsfristen</Typography>