Implement direct login functionality with email and password

- Update login API to support direct authentication via email and password, removing the OAuth2 redirect flow.
- Modify LoginForm component to include password field and validation.
- Refactor useAuth composable to handle login with both email and password.
- Remove unnecessary OAuth2 callback handler and PKCE utilities.
- Update relevant documentation and error handling for the new login method.

app/components/Auth/LoginForm.vue

@@ -11,6 +11,7 @@ const { login } = useAuth()
 const loginSchema = toTypedSchema(
   z.object({
     email: z.string().email('Bitte geben Sie eine gültige E-Mail-Adresse ein'),
+    password: z.string().min(8, 'Passwort muss mindestens 8 Zeichen lang sein'),
   })
 )
 
@@ -27,7 +28,7 @@ const onSubmit = handleSubmit(async (values) => {
   submitError.value = null
 
   try {
-    await login(values.email)
+    await login(values.email, values.password)
     // Redirect happens in login() function
   } catch (error: any) {
     console.error('Login error:', error)
@@ -55,6 +56,17 @@ const onSubmit = handleSubmit(async (values) => {
       </FormItem>
     </FormField>
 
+    <!-- Password Field -->
+    <FormField v-slot="{ componentField }" name="password">
+      <FormItem>
+        <FormLabel class="text-white/90 text-base font-medium">Passwort</FormLabel>
+        <FormControl>
+          <Input type="password" placeholder="••••••••" v-bind="componentField" />
+        </FormControl>
+        <FormMessage />
+      </FormItem>
+    </FormField>
+
     <!-- Submit Button -->
     <Button type="submit" variant="experimenta" size="experimenta" class="w-full" :disabled="isSubmitting">
       <Loader2 v-if="isSubmitting" class="mr-2 h-5 w-5 animate-spin" />
@@ -63,7 +75,7 @@ const onSubmit = handleSubmit(async (values) => {
 
     <!-- Info Text -->
     <p class="text-sm text-white/70 text-center">
-      Sie werden zur sicheren Anmeldeseite weitergeleitet
+      Anmeldung erfolgt verschlüsselt über unseren Partner Cidaas
     </p>
   </form>
 </template>