Fix 500 on POST /api/projects/:id/members — add project_invite types to notification CHECK constraint

The invite_members handler called create_notification with type="project_invite", which
is not in the ck_notifications_type CHECK constraint. The db.flush() inside the handler
flushed both the ProjectMember and Notification INSERTs atomically, causing a
CheckViolationError → 500. Added "project_invite", "project_invite_accepted",
"project_invite_rejected" to the model tuple and migration 060 drops/recreates the
constraint to include them.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/alembic/versions/060_expand_notification_types_project.py

@@ -0,0 +1,35 @@
+"""Expand notification type CHECK for project invite types
+
+Revision ID: 060
+Revises: 059
+"""
+from alembic import op
+
+revision = "060"
+down_revision = "059"
+branch_labels = None
+depends_on = None
+
+_OLD_TYPES = (
+    "connection_request", "connection_accepted", "connection_rejected",
+    "calendar_invite", "calendar_invite_accepted", "calendar_invite_rejected",
+    "event_invite", "event_invite_response",
+    "info", "warning", "reminder", "system",
+)
+_NEW_TYPES = _OLD_TYPES + (
+    "project_invite", "project_invite_accepted", "project_invite_rejected",
+)
+
+
+def _check_sql(types: tuple) -> str:
+    return f"type IN ({', '.join(repr(t) for t in types)})"
+
+
+def upgrade() -> None:
+    op.drop_constraint("ck_notifications_type", "notifications", type_="check")
+    op.create_check_constraint("ck_notifications_type", "notifications", _check_sql(_NEW_TYPES))
+
+
+def downgrade() -> None:
+    op.drop_constraint("ck_notifications_type", "notifications", type_="check")
+    op.create_check_constraint("ck_notifications_type", "notifications", _check_sql(_OLD_TYPES))

backend/app/models/notification.py

@@ -9,6 +9,7 @@ _NOTIFICATION_TYPES = (
     "connection_request", "connection_accepted", "connection_rejected",
     "calendar_invite", "calendar_invite_accepted", "calendar_invite_rejected",
     "event_invite", "event_invite_response",
+    "project_invite", "project_invite_accepted", "project_invite_rejected",
     "info", "warning", "reminder", "system",
 )