docs: add inline documentation where missing

src/Validator/Constraints/Participant.php

@@ -1,9 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\Validator\Constraints;
 
 use Symfony\Component\Validator\Constraint;
 
+/**
+ * Validates participant data for cross-field consistency.
+ *
+ * Applied as a class-level constraint on ParticipantDto to enforce business rules
+ * that depend on multiple fields (e.g., requiring pickup when bus transport is selected).
+ */
 #[\Attribute]
 class Participant extends Constraint
 {

src/Validator/Constraints/ParticipantValidator.php

@@ -1,11 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\Validator\Constraints;
 
 use App\Form\Model\ParticipantDto;
 use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidator;
 
+/**
+ * Validates cross-field constraints on participant data.
+ *
+ * Enforces business rules that require examining multiple fields together,
+ * such as requiring a pickup location when bus transportation is selected.
+ */
 class ParticipantValidator extends ConstraintValidator
 {
     public function validate(mixed $value, Constraint $constraint): void

src/Validator/Constraints/PromoVoucherValidator.php

@@ -11,6 +11,13 @@ use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidator;
 use Symfony\Component\Validator\Exception\UnexpectedTypeException;
 
+/**
+ * Validates promotional voucher codes against the BPN API.
+ *
+ * Verifies that promo codes are valid for the current travel, checks minimum price
+ * thresholds, and validates code availability. Uses the participant's calculated
+ * total price (including room and all selected services) for threshold comparison.
+ */
 class PromoVoucherValidator extends ConstraintValidator
 {
     public function __construct(

src/Validator/Constraints/PurchaseVoucherValidator.php

@@ -10,6 +10,12 @@ use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidator;
 use Symfony\Component\Validator\Exception\UnexpectedTypeException;
 
+/**
+ * Validates purchase voucher codes against the BPN API.
+ *
+ * Verifies that voucher codes exist and have remaining balance. Unlike promo
+ * vouchers, purchase vouchers do not require travel or price context validation.
+ */
 class PurchaseVoucherValidator extends ConstraintValidator
 {
     public function __construct(

src/Validator/Constraints/RoomSelection.php

@@ -6,6 +6,13 @@ namespace App\Validator\Constraints;
 
 use Symfony\Component\Validator\Constraint;
 
+/**
+ * Validates room selection requirements for bookings.
+ *
+ * Applied as a class-level constraint on BookingDto to ensure valid room
+ * configurations: at least one room must be selected, and baby rooms
+ * cannot be booked without accompanying regular rooms.
+ */
 #[\Attribute]
 class RoomSelection extends Constraint
 {

src/Validator/Constraints/RoomSelectionValidator.php

@@ -10,6 +10,12 @@ use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidator;
 use Symfony\Component\Validator\Exception\UnexpectedTypeException;
 
+/**
+ * Validates room selection business rules for bookings.
+ *
+ * Enforces that at least one room is selected and that baby rooms (BABY code)
+ * are only booked in combination with regular rooms, not standalone.
+ */
 class RoomSelectionValidator extends ConstraintValidator
 {
     public function validate(mixed $value, Constraint $constraint): void