feat: add AI descriptions and platform submission checks

backend/migrations/versions/0012_description_model.py

@@ -0,0 +1,19 @@
+"""Independent description model using the existing shared provider connection."""
+
+import sqlalchemy as sa
+from alembic import op
+
+revision = "0012"
+down_revision = "0011"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.add_column(
+        "ai_settings", sa.Column("description_model", sa.String(200), nullable=False, server_default="")
+    )
+
+
+def downgrade():
+    op.drop_column("ai_settings", "description_model")