docs(ios): clarify beta archive auth

apps/ios/README.md

@@ -56,7 +56,7 @@ Prereqs:
 - `xcodegen`
 - `fastlane`
 - Apple account signed into Xcode for automatic signing/provisioning
-- App Store Connect API key set up in Keychain via `scripts/ios-asc-keychain-setup.sh`
+- App Store Connect API key set up in Keychain via `scripts/ios-asc-keychain-setup.sh` when auto-resolving a beta build number or uploading to TestFlight
 
 Release behavior:
 

apps/ios/fastlane/SETUP.md

@@ -60,6 +60,13 @@ cd apps/ios
 fastlane ios auth_check
 ```
 
+ASC auth is only required when:
+
+- uploading to TestFlight
+- auto-resolving the next build number from App Store Connect
+
+If you pass `--build-number` to `pnpm ios:beta:archive`, the local archive path does not need ASC auth.
+
 Archive locally without upload:
 
 ```bash