RFC-0023: World Transaction

Status: Normative. States are OPEN -> PREPARED -> VALIDATED -> COMMITTED|ABORTED; no other transition exists. A transaction contains base world version, read/write/create/destroy sets, ordered events, and capability tokens. Validation order: state, capability, entity generation, schema, ownership epoch, read/version conflict, write conflict, deterministic ordering. Commit atomically applies the complete write set to one authoritative region and increments WorldVersion once; events appear only after success. Policies are Reject, Merge, LastWriterByPriority, CommutativeMerge; the latter requires registered associative+commutative semantics. Any failure aborts with no mutation.