BlogGen Connector v1.1.19 — Force Original Attachment Image Compression

Fixes cases where the Media Library still shows the original 2 MB PNG after publishing.

Changes:
- Hard-compresses the actual attachment file WordPress stores.
- Converts large imported BlogGen images to compressed JPG.
- Repoints the attachment to the compressed file.
- Deletes old oversized original file and stale subsizes where possible.
- Regenerates attachment metadata from the compressed file.
- Adds a secure diagnostic endpoint to optimise an existing attachment by ID.
- Keeps v1.1.18 visible Meta description stripping.
