social.twinkl.homepage.tile

A placed Web Tile on the actor's customizable home page. Inspired by the DASL tile proposal (darobin/dasl.ing#95) but adapted for Twinkl v1: tile resources carry inline content + contentType rather than content-addressed `src` (no CID infrastructure yet), so the structure can gain an optional `src` later without breaking. Geometry is co-located on the record (8-column grid). The tile payload renders in a null-origin sandboxed iframe.