Complete M11 Creator Studio and M12 Trust & Safety for PC5

- Creator Studio: Visual behavior & property inspector, GLB model importer, binary persistence
- Trust & Safety: 18+ TOS confirmation (DOB removed), creator guidelines & briefing card on join, in-game reporting HUD
- Test Harness: Add --filter, --skip-backend, --skip-godot to run_checkpoint_tests.py

backend/alembic/versions/0016_content_guidelines.py

@@ -0,0 +1,30 @@
+"""add content_guidelines column to worlds table
+
+Revision ID: 0016_content_guidelines
+Revises: 0015_add_discovery_metadata
+Create Date: 2026-09-17 00:00:00.000000
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision: str = "0016_content_guidelines"
+down_revision: Union[str, None] = "0015_add_discovery_metadata"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # Check if column already exists (in case partial run added column before version update failed)
+    bind = op.get_bind()
+    insp = sa.inspect(bind)
+    cols = [c["name"] for c in insp.get_columns("worlds")]
+    if "content_guidelines" not in cols:
+        op.add_column("worlds", sa.Column("content_guidelines", sa.Text(), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("worlds", "content_guidelines")