Didi gets a face and a voice — chat v0, curator verbs, and the inbox-curation skill

Step 8 of the humain-vc unlock build order: the chat rail is now didi, it can file a captured link under an existing thesis by name in one turn, and it has an actual face — a character headshot composited with the shell's own brand gradient. Deliberately scoped to augment-it alone; the cross-service didi vision has its own exploration doc and its own timeline.