feat: implement user management system

- Add role field to UserProfile (superadmin/admin/trainer)
- Add role-based permission classes
- Create UserManagementViewSet with CRUD and password change
- Add API types and components for user management
- Create users management page in settings
- Only superadmins can manage users

frontend/src/components/users/user-form.tsx

@@ -0,0 +1,160 @@
+"use client"
+
+import { useState } from "react"
+import { Button } from "@/components/ui/button"
+import { Input } from "@/components/ui/input"
+import { Label } from "@/components/ui/label"
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogHeader,
+  DialogTitle,
+} from "@/components/ui/dialog"
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "@/components/ui/select"
+import { ICreateUserInput, IUpdateUserInput, IUser } from "@/lib/api"
+
+interface UserFormProps {
+  open: boolean
+  onOpenChange: (open: boolean) => void
+  onSubmit: (data: ICreateUserInput | IUpdateUserInput) => Promise<void>
+  user?: IUser
+  mode: 'create' | 'edit'
+}
+
+const roles = [
+  { value: 'superadmin', label: 'Super Admin' },
+  { value: 'admin', label: 'Admin' },
+  { value: 'trainer', label: 'Trainer' },
+]
+
+export function UserForm({ open, onOpenChange, onSubmit, user, mode }: UserFormProps) {
+  const [loading, setLoading] = useState(false)
+  const [formData, setFormData] = useState<ICreateUserInput | IUpdateUserInput>({
+    username: user?.username || '',
+    email: user?.email || '',
+    first_name: user?.first_name || '',
+    last_name: user?.last_name || '',
+    password: '',
+    role: (user?.role as any) || 'trainer',
+  })
+
+  const handleSubmit = async (e: React.FormEvent) => {
+    e.preventDefault()
+    setLoading(true)
+    try {
+      await onSubmit(formData)
+      onOpenChange(false)
+    } finally {
+      setLoading(false)
+    }
+  }
+
+  return (
+    <Dialog open={open} onOpenChange={onOpenChange}>
+      <DialogContent className="sm:max-w-[500px]">
+        <DialogHeader>
+          <DialogTitle>
+            {mode === 'create' ? 'Neuer Benutzer' : 'Benutzer bearbeiten'}
+          </DialogTitle>
+          <DialogDescription>
+            {mode === 'create' 
+              ? 'Erstelle einen neuen Benutzer mit Rolle' 
+              : 'Bearbeite die Benutzerdaten'}
+          </DialogDescription>
+        </DialogHeader>
+        
+        <form onSubmit={handleSubmit} className="space-y-4">
+          <div className="grid grid-cols-2 gap-4">
+            <div className="space-y-2">
+              <Label htmlFor="firstName">Vorname</Label>
+              <Input
+                id="firstName"
+                value={formData.first_name}
+                onChange={(e) => setFormData({ ...formData, first_name: e.target.value })}
+                required
+              />
+            </div>
+            <div className="space-y-2">
+              <Label htmlFor="lastName">Nachname</Label>
+              <Input
+                id="lastName"
+                value={formData.last_name}
+                onChange={(e) => setFormData({ ...formData, last_name: e.target.value })}
+                required
+              />
+            </div>
+          </div>
+          
+          <div className="space-y-2">
+            <Label htmlFor="username">Username</Label>
+            <Input
+              id="username"
+              value={formData.username}
+              onChange={(e) => setFormData({ ...formData, username: e.target.value })}
+              required
+            />
+          </div>
+          
+          <div className="space-y-2">
+            <Label htmlFor="email">E-Mail</Label>
+            <Input
+              id="email"
+              type="email"
+              value={formData.email}
+              onChange={(e) => setFormData({ ...formData, email: e.target.value })}
+              required
+            />
+          </div>
+          
+          {mode === 'create' && (
+            <div className="space-y-2">
+              <Label htmlFor="password">Passwort</Label>
+              <Input
+                id="password"
+                type="password"
+                value={formData.password}
+                onChange={(e) => setFormData({ ...formData, password: e.target.value })}
+                required={mode === 'create'}
+              />
+            </div>
+          )}
+          
+          <div className="space-y-2">
+            <Label htmlFor="role">Rolle</Label>
+            <Select
+              value={formData.role}
+              onValueChange={(value) => setFormData({ ...formData, role: value as any })}
+            >
+              <SelectTrigger>
+                <SelectValue placeholder="Rolle auswählen" />
+              </SelectTrigger>
+              <SelectContent>
+                {roles.map((role) => (
+                  <SelectItem key={role.value} value={role.value}>
+                    {role.label}
+                  </SelectItem>
+                ))}
+              </SelectContent>
+            </Select>
+          </div>
+          
+          <div className="flex justify-end gap-2 pt-4">
+            <Button type="button" variant="outline" onClick={() => onOpenChange(false)}>
+              Abbrechen
+            </Button>
+            <Button type="submit" disabled={loading}>
+              {loading ? 'Speichern...' : 'Speichern'}
+            </Button>
+          </div>
+        </form>
+      </DialogContent>
+    </Dialog>
+  )
+}

frontend/src/lib/api.ts

@@ -265,6 +265,27 @@ export interface IUser {
   last_name?: string
   club_id?: number | null
   club_name?: string | null
+  is_active?: boolean
+  role?: string
+  date_joined?: string
+}
+
+export interface ICreateUserInput {
+  username: string
+  email: string
+  first_name: string
+  last_name: string
+  password: string
+  role: 'superadmin' | 'admin' | 'trainer'
+}
+
+export interface IUpdateUserInput {
+  username?: string
+  email?: string
+  first_name?: string
+  last_name?: string
+  is_active?: boolean
+  role?: 'superadmin' | 'admin' | 'trainer'
 }
 
 export interface IAuthResponse {