* test(site-replication): pin MinIO IAMUserType wire semantics for policy mappings
Red tests for P0-4: MinIO peers send SRPolicyMapping.UserType using the
madmin IAMUserType table (unknown=-1, regUser=0, stsUser=1, svcUser=2),
while RustFS deserializes the field as u64 and decodes it with the
internal RPC table (None=0, Svc=1, Sts=2, Reg=3).
- userType -1 (MinIO group mappings) fails to deserialize, rejecting the
whole IAM item: group mappings never sync from MinIO.
- stsUser=1 decodes as Svc, landing federated STS mappings under the
wrong prefix and silently dropping their effect.
* fix(site-replication): translate policy mapping userType at MinIO wire boundary
SRPolicyMapping.userType travels on the wire using MinIO's IAMUserType
table (unknown=-1, regUser=0, stsUser=1, svcUser=2), but RustFS stored
the field as u64 and reused the internal RPC encoding
UserType::to_u64/from_u64 (None=0, Svc=1, Sts=2, Reg=3) at the site
replication boundary. Consequences: MinIO group mappings (userType -1)
failed to deserialize and the whole IAM item was rejected, and MinIO STS
mappings (1) were stored as service-account mappings, silently dropping
federated users' policies.
- Widen SRPolicyMapping.user_type and SRCredInfo.iam_user_type to i64 so
MinIO's -1 deserializes.
- Add sr_wire_user_type / user_type_from_sr_wire in rustfs-iam as the
dedicated SR wire codec: MinIO table on both directions, groups always
encoded as 0, and wire value 3 kept forever as an alias for Reg so
mappings from pre-fix RustFS peers still decode; unknown values fail
closed.
- Route the SR inbound (apply_iam_item) and outbound
(mapped_policy_to_sr_mapping, policy-mapping change hooks) paths
through the codec.
The internal UserType::to_u64/from_u64 encoding is untouched: it is the
intra-cluster node RPC contract and changing it would break rolling
restarts. Outbound compatibility with old RustFS peers is preserved
because UserType::None and Reg share the users prefix in
get_mapped_policy_path, so wire 0 lands in the same location Reg=3 did.
