fix: validate newly entered phone numbers

src/Form/Model/ParticipantDto.php

@@ -93,8 +93,17 @@ class ParticipantDto
     )]
     public ?string $email = null;
 
+    #[Assert\When(
+        expression: 'this.isMobileNewlyEntered()',
+        constraints: [new AppAssert\PhoneNumber()],
+        groups: ['booking_edit', 'booking_create'],
+    )]
     public ?string $mobile = null;
 
+    // The number as loaded from BusPro, which goes back unchanged and is exempt from PhoneNumber.
+    // Public so it survives the session round trip through __unserialize().
+    public ?string $loadedMobile = null;
+
     #[Assert\Valid(groups: ['booking_edit', 'booking_create'])]
     #[Assert\NotNull(message: 'Bitte Adresse angeben', groups: ['applicant_address'])]
     public ?Address $address = null;
@@ -240,6 +249,7 @@ class ParticipantDto
         $instance->nationality = $personalData->nationality ?: 'D';
         $instance->email = $personalData->communication->email;
         $instance->mobile = $personalData->communication->mobile;
+        $instance->loadedMobile = $personalData->communication->mobile;
         $instance->dateOfBirth = $personalData->dateOfBirth;
         $instance->height = $personalData->height;
         $instance->weight = $personalData->weight;
@@ -254,6 +264,11 @@ class ParticipantDto
         return $instance;
     }
 
+    public function isMobileNewlyEntered(): bool
+    {
+        return AppAssert\PhoneNumber::isNewlyEntered($this->mobile, $this->loadedMobile);
+    }
+
     public function isApplicant(): bool
     {
         return 0 === $this->index;