Support macos-native-credential-sync feature flag, similar to Windows

Summary Vaultwarden already supports the Windows native credential sync feature flag (windows-native-credential-sync), as implemented in #7798 and documented in #7841. Meanwhile, Bitwarden has released the macOS native AutoFill extension in its stable desktop client. However, the corresponding macos-native-credential-sync feature flag is still not supported by Vaultwarden. Current Status • Windows: windows-native-credential-sync is already included in Vaultwarden's supported feature flags. • macOS: Bitwarden defines macos-native-credential-sync, and the macOS AutoFill extension has been released in the stable desktop client (2026.10.2). • Vaultwarden: The macOS feature flag is not included in the supported feature flag list. Feature Request Could Vaultwarden add support for macos-native-credential-sync, similar to the existing Windows implementation? This would allow macOS users to enable the native credential provider integration when usi…