Guard ImageKit asset sync and cleanup when remote assets belong to another environment

When development and production share the same ImageKit account, a database/files sync from production to development can cause development to act on production-owned remote assets. This follow-up should make the ImageKit integration store an environment marker on remote asset rows, append the configured environment to the effective upload folder, block remote sync and cleanup when the stored asset owner environment does not match the current runtime environment, and surface that blocked state clearly in status/admin output. This prevents accidental cross-environment mutation while preserving the existing lazy delivery workflow.