feat: add agent hashes, support all mechs from legacy factories

[Tanya-atatakai]

1. support old agent factories to track more mechs
2. make it so mech contract (request/deliver events) is tracked automatically from createMech event
3. implement mech agent entity with latest agent hash and agent id

this query can be used to retrieve the latest hash

{
  mechAgents {
    id // agent number, e.g. 1, 2
    mech // mech address
    agentHash // latest agent hash
  }
}