[solo applicant] add a new variant to a parent without making it auto-render

Proof set for Iterate profile (add new experience as quarry node — does not auto-render)

Cover G9 quarry gestures: iterating a personal-info field updates the FIXED-tier node and refreshes the header layout; a quarry node added under children[] does NOT render unless selection.active[] picks it (the tree-of-choices contract); deleting a variant-pool wrapper does NOT silently flatten its inactive members — they remain intentional quarry memory; adding a new language code seeds a complete peer cv_profile.<lang>.tree (and cl) without cross-language inheritance.