- enable B1/B2/B4 source-shape-aware F13 placement behind env flag - align F13 placement_trace with mapper top_bullets cardinality - preserve canonical render output when flag is off
- add dormant placement planner integrating B1 / B2 / B3 - region 1:1 sub_zone mapping with narrowest-accepts-first heuristic - frame selection by accepted_content_types coverage + declaration order