Function classify_epistemic_state 

pub fn classify_epistemic_state(
    quins: &[NQuin],
    agent_did: u64,
    proposition_hash: u64,
) -> EpistemicState

Classify the epistemic state of agent_did regarding proposition_hash.

Scans the quin slice for modality predicates in the agent’s epistemic context and returns the highest-confidence classification found. The precedence order is: ObjectiveKnowledge > InferredBelief > HearsayBelief > Unknown

This is an O(n) linear scan — for production use, maintain a hash index on (context, predicate) pairs.