Describe AuthorizeBatch semantics (all-or-nothing, single-entity-type,
single-organization, batch attribute requirement, audit logging), the
authz.NewBatchAuthorizeFunc / WithBatch* helpers, the MCP
Resolver.AuthorizeBatch entry point, and the new batch-style
AuthorizationAttributes implementation contract (non-empty,
deduplicated, same-entity-type input; only found rows returned).
Signed-off-by: Bryan Frimin <bryan@probo.com>