Pure module game/sim/techgraph: PrereqsMet (AND of ORs, empty group fails),
SetResearched (stamps, child-cost sweep, sticky turnAvailable, zero-cost
recursion) and the newly-available collector, all read out of 0x00581e10,
0x0057d8e0 and 0x00587cc3.
Wired into the B3 hook in compare mode only, over the scratch node copies:
four more node write-backs, the EVENT_TECHS_UNLOCKED list (still an input,
still nullptr when it could not be computed), the de-duplicating observed-tech
append and the one RNG word RollResearchEvent draws.
docs/U-unlock.md section 4 is the prediction, written before the build was staged.
