v9.23.0 — Instagram delete posts

Adds the 'remove old posts' action to caspian-instagram: new admin callable deleteInstagramMedia({ mediaId }) that deletes a published post via DELETE /{ig-media-id} on the stored Page token (whole post/reel/carousel album, not a single slide). Requires instagram_manage_contents on the token (Facebook-Login only). No consumer action required (additive; redeploy caspian-instagram and reconnect accounts linked before this).