feat: hide event types from SAC UI via Settings checkbox (0.20.23)

Per-type «Показывать в событиях» in severity settings; filters lists, dashboard, hosts, and problems.

backend/alembic/versions/023_event_type_visibility.py

@@ -0,0 +1,34 @@
+"""event type visibility settings
+
+Revision ID: 023_event_type_visibility
+Revises: 022_host_remote_action
+Create Date: 2026-06-21
+
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+revision = "023_event_type_visibility"
+down_revision = "022_host_remote_action"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "event_type_visibility",
+        sa.Column("event_type", sa.String(length=128), nullable=False),
+        sa.Column("show_in_events", sa.Boolean(), nullable=False),
+        sa.Column(
+            "updated_at",
+            sa.DateTime(timezone=True),
+            server_default=sa.text("now()"),
+            nullable=False,
+        ),
+        sa.PrimaryKeyConstraint("event_type"),
+    )
+
+
+def downgrade() -> None:
+    op.drop_table("event_type_visibility")