feat: add first_name and last_name fields to UserTenant model and sync with Keycloak

Co-authored-by: Copilot <copilot@github.com>

backend/alembic/versions/a1b2c3d4e5f6_add_name_fields_to_user_tenants.py

@@ -0,0 +1,35 @@
+"""add first_name and last_name to user_tenants
+
+Revision ID: a1b2c3d4e5f6
+Revises: 8c9bad3da37f
+Create Date: 2026-05-06 00:00:00.000000
+
+"""
+from typing import Sequence, Union
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "a1b2c3d4e5f6"
+down_revision: Union[str, None] = "8c9bad3da37f"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "user_tenants",
+        sa.Column("first_name", sa.String(100), nullable=True,
+                  comment="Nombre (caché local de Keycloak)"),
+        schema="core",
+    )
+    op.add_column(
+        "user_tenants",
+        sa.Column("last_name", sa.String(100), nullable=True,
+                  comment="Apellido (caché local de Keycloak)"),
+        schema="core",
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("user_tenants", "last_name", schema="core")
+    op.drop_column("user_tenants", "first_name", schema="core")