sqla (mapping): fix missing PEP constraint:

A constraint name was missing on the `PubsubNode.pep` column, resulting in a crash when
trying to generate the initial database on launch with an empty `local_dir`.

Migration script introducing the column (f4cb5fc600c7_add_missing_pep_check_constraint.py)
has been updated too. Another migration script has been made to add the constraint to
existing DB (only if they are missing).

libervia/backend/memory/migration/versions/007439b3b0ce_add_pep_to_pubsubnode.py

@@ -21,7 +21,7 @@ def upgrade():
         batch_op.add_column(
             sa.Column(
                 "pep",
-                sa.Boolean(create_constraint=True),
+                sa.Boolean(create_constraint=True, name="pep_bool"),
                 server_default=sa.text("0"),
                 nullable=False,
             )

libervia/backend/memory/migration/versions/f4cb5fc600c7_add_missing_pep_check_constraint.py

@@ -0,0 +1,40 @@
+"""add missing pep check constraint
+
+Revision ID: f4cb5fc600c7
+Revises: ccd879fef17e
+Create Date: 2026-06-20 10:07:46.457551
+
+"""
+
+from alembic import op
+from sqlalchemy import inspect
+
+# revision identifiers, used by Alembic.
+revision = "f4cb5fc600c7"
+down_revision = "ccd879fef17e"
+branch_labels = None
+depends_on = None
+
+
+def _existing_check_constraints(table_name: str) -> set[str | None]:
+    insp = inspect(op.get_bind())
+    return {c["name"] for c in insp.get_check_constraints(table_name) if c.get("name")}
+
+
+def upgrade():
+    existing = _existing_check_constraints("pubsub_nodes")
+
+    if "ck_pubsub_nodes_pep_bool" not in existing:
+        with op.batch_alter_table("pubsub_nodes") as batch_op:
+            batch_op.create_check_constraint(
+                "ck_pubsub_nodes_pep_bool",
+                "pep IN (0, 1)",
+            )
+
+
+def downgrade():
+    existing = _existing_check_constraints("pubsub_nodes")
+
+    if "ck_pubsub_nodes_pep_bool" in existing:
+        with op.batch_alter_table("pubsub_nodes") as batch_op:
+            batch_op.drop_constraint("ck_pubsub_nodes_pep_bool", type_="check")

libervia/backend/memory/sqla_mapping.py

@@ -629,7 +629,7 @@ class PubsubNode(Base):
     service = Column(JID)
     name = Column(Text, nullable=False)
     pep = Column(
-        Boolean(create_constraint=True),
+        Boolean(create_constraint=True, name="pep_bool"),
         nullable=False,
         server_default=false(),
     )