Run Apple cache setup outside Nix shell

evolution/proposals/BEP-0009-release-infrastructure-and-store-upload-pipeline.md

@@ -50,7 +50,9 @@ The same change also makes the forge itself the release authority: release tags
   Cache setup is optional release acceleration: Bazel-only cache steps must not
   install filesystem-cache helpers such as `spacectl`, and Namespace cache
   probes must be timeout-bounded so Apple builds can continue without the
-  remote cache.
+  remote cache. Apple workflows should call the fail-open cache helper directly
+  instead of entering the full Nix development shell just to decide whether a
+  cache is available.
 - Produce unsigned Apple validation artifacts when signing is absent, but require signing for an App Store requested iOS release and for a Sparkle tester release. Uploadable artifacts are produced only after provisioning profiles can be synced from App Store Connect credentials and the relevant Apple certificate is proven to match the selected Google KMS key.
 - Resolve release credentials through age/agenix before signed Apple lanes run. Forgejo secrets should carry only the runner age identity fallback and the Authentik WIF client secret until OpenBao can mint the runner token directly. App Store Connect keys and signing certificates live as sealed files under `secrets/`.
 - Persist the forge runner SSH key as `/var/lib/forgejo-runner-agent/age_keystore` and export `BURROW_RUNNER_AGE_IDENTITY_PATH` so jobs can resolve agenix identities without embedding long-lived material in every workflow.