fix: clients read the professional's real agenda, not their own

/services/public-calendar/{professionalId} exists after all — the web has been
using it all along. My earlier probes missed it because they guessed the URL
shape, and because it is keyed by the professionals row id rather than the
owning user id, which ProfessionalEntity was discarding.

Adds ProfessionalEntity.recordId and points the client calendar at the public
endpoint. Until now a client browsing a professional's availability was served
their own agenda, so every slot looked free and two people could book the same
hour. A failed load now hides the slots and offers a retry instead of showing
them as available.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/professional_repository/lib/src/entities/professional_entity.dart

@@ -21,6 +21,11 @@ class ProfessionalEntity extends Equatable {
   final PaymentMethodEntity paymentMethods;
   final int slotDurationMinutes;
 
+  /// Row id in the `professionals` table. Distinct from [id], which is the
+  /// owning user's id. Endpoints such as /services/public-calendar are keyed
+  /// by this one.
+  final String recordId;
+
   const ProfessionalEntity({
     required this.id,
     required this.identification,
@@ -40,6 +45,7 @@ class ProfessionalEntity extends Equatable {
     required this.schedules,
     required this.paymentMethods,
     this.slotDurationMinutes = 120,
+    this.recordId = '',
   });
 
   static ProfessionalEntity fromDocument(Map<String, dynamic> doc) {
@@ -64,6 +70,7 @@ class ProfessionalEntity extends Equatable {
       paymentMethods: PaymentMethodEntity.fromDocument(doc['payment_methods']),
       slotDurationMinutes:
           (doc['slot_duration_minutes'] as num?)?.toInt() ?? 120,
+      recordId: doc['id']?.toString() ?? '',
     );
   }
 
@@ -86,6 +93,7 @@ class ProfessionalEntity extends Equatable {
     Schedules? schedules,
     PaymentMethodEntity? paymentMethods,
     int? slotDurationMinutes,
+    String? recordId,
   }) {
     return ProfessionalEntity(
       id: id ?? this.id,
@@ -108,6 +116,7 @@ class ProfessionalEntity extends Equatable {
       schedules: schedules ?? this.schedules,
       paymentMethods: paymentMethods ?? this.paymentMethods,
       slotDurationMinutes: slotDurationMinutes ?? this.slotDurationMinutes,
+      recordId: recordId ?? this.recordId,
     );
   }
 
@@ -154,6 +163,7 @@ class ProfessionalEntity extends Equatable {
         schedules,
         paymentMethods,
         slotDurationMinutes,
+        recordId,
       ];
 
   @override

packages/professional_repository/lib/src/repositories/api_professional_repository.dart

@@ -195,6 +195,7 @@ class ApiProfessionalRepository {
           : PaymentMethodEntity.empty,
       slotDurationMinutes:
           (json['slot_duration_minutes'] as num?)?.toInt() ?? 120,
+      recordId: json['id']?.toString() ?? '',
     );
   }