1424a21419
Add a secret:NAME arm to GalaxySecretRef.ResolveApiKey that resolves the Galaxy gateway API key through the shared ISecretResolver — fail-closed if the secret is absent (never falls through to the cleartext literal arm), retiring the dev:/literal in-DB path for production. Because GetAsync is async the method becomes ResolveApiKeyAsync; the await cascade threads ISecretResolver by ctor injection into GalaxyDriver + GalaxyDriverBrowser and (since GalaxyDriver is built by a static factory closure, not DI) through GalaxyDriverFactoryExtensions + DriverFactoryBootstrap (which pulls the real resolver from the service provider — registered unconditionally in Slice 1). A NullSecretResolver null-object backs the parse-only/test paths only; the runtime path always gets the real resolver (verified end-to-end). TDD: 3 new secret:-arm tests (resolve / fail-closed-on-absent / no-literal-warning) RED without the arm, GREEN with it; 338 Galaxy tests pass; no sync-over-async.