services.hyperhive.c0re.swaggerUiTheme -> services.hyperhive.gateway.swaggerUiTheme.
hive-c0re has no relationship to this option (it's consumed entirely
by the gateway's nginx config) since the previous two commits moved
the theme files out of hive-c0re/ and gateway to hosting the whole
dist itself — the option shouldn't live in c0re's namespace either.
Pure option move: default wiring in flake.nix now sets
services.hyperhive.gateway.swaggerUiTheme instead of the c0re one;
hive-gateway/default.nix reads it via the module's own already-bound
cfg (services.hyperhive.gateway) instead of reaching into c0re's.
Verified: nix build .#swagger-ui-theme unaffected (same store path,
pure option-plumbing change, no content change); a full nixosSystem
eval of nixosModules.default resolves the option at its new path and
confirms the gateway's /api/docs/ location still aliases the correct
store path.