Function assert_objective_knowledge 

pub fn assert_objective_knowledge(
    agent_did: u64,
    proposition_hash: u64,
    proof_hash: u64,
    ts: u64,
) -> [NQuin; 3]

Record that agent_did has ObjectiveKnowledge of proposition_hash, justified by proof_hash (e.g. a q42ep:CryptoSensor or q42ep:SignedObjectiveEvent).

Returns 3 quins in agent_epistemic_context(agent_did):

1. agent_did → knowsDirectly → proposition_hash (epistemic modality)
2. agent_did → cog:believes → proposition_hash (CogAI belief relation)
3. proposition_hash → prov:wasGeneratedBy → proof_hash (justification chain)