Batch skillXp then resetPerkState with XP rollback; 400 for invalid skillXp;
MasteryFixtureApi gate tests; README fixture vs grant semantics; Bruno GET playerId.
Replace fixture player ids with POST …/__dev/mastery-fixture (resetPerkState,
absolute skillXp). Bruno deny tests set state in pre-request on dev-local-1.
Gated to Development/Testing or Game:EnableMasteryFixtureApi.
Seed neo48-perk-fresh and neo48-perk-branch via Game:FixturePlayerIds;
level_too_low uses isolated fresh player, branch_already_chosen sets up
neo48-perk-branch in pre-request instead of skipping on shared state.
VinPropane