Function render_initial_migration 

pub fn render_initial_migration(schema: &IntrospectedSchema) -> MigrationFile

Render the introspected schema as a MigrationFile suitable for writing to migrations/<INSPECTED_PLUGIN_NAME>/0001_initial.json. One CreateTable per introspected table; snapshot_after captures the imported state so subsequent make_in runs diff against it.

Filled in by subagent B.