b8037b9b22
openfut-identity: durable, reversible (game_id, entity_kind, core_id) <-> external wire id mapping. Game-independent infrastructure (adapters supply the numeric policy via base_floor; the store guarantees stable/unique/reversible/ game-scoped/persistent/atomic/explicit). JSON-file backed behind an ExternalIdentityStore trait (SQLite can drop in later); parking_lot-guarded, atomic temp+rename persist, rejects a torn reverse-duplicate on open. Core never learns FIFA integers; only the host/adapter that owns a game boundary uses this. 6 tests, 4/4 mutations killed (same-id-for-two-items, lost-on-restart, broken-reverse, dropped-game-scope). Phase commit 1/5.