Rename agent/ to user/ and poc-agent binary to consciousness

Mechanical rename: src/agent/ -> src/user/, all crate::agent:: ->
crate::user:: references updated. Binary poc-agent renamed to
consciousness with CLI name and user-facing strings updated.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/thought/context.rs

@@ -4,7 +4,7 @@
 // Journal entries are loaded from the memory graph store, not from
 // a flat file — the parse functions are gone.
 
-use crate::agent::types::*;
+use crate::user::types::*;
 use chrono::{DateTime, Utc};
 use tiktoken_rs::CoreBPE;