Reduce pub visibility in agent::api and user modules

api/: parsing module private, SamplingParams/StreamEvent/StreamResult/
AbortOnDrop/build_response_message/collect_stream to pub(crate).
Internal types (ChatRequest, ChunkChoice, Delta, etc.) to pub(crate).
StreamResult fields to pub(crate). Parsing functions to pub(super).

user/: context, subconscious, unconscious, thalamus modules private
(only chat needs pub(crate) for mind/ access).

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

src/user/mod.rs

@@ -3,11 +3,11 @@
 // TUI, UI channel, parsing. The cognitive layer (session state
 // machine, DMN, identity) lives in mind/.
 
-pub mod chat;
-pub mod context;
-pub mod subconscious;
-pub mod unconscious;
-pub mod thalamus;
+pub(crate) mod chat;
+mod context;
+mod subconscious;
+mod unconscious;
+mod thalamus;
 
 use anyhow::Result;
 use std::io::Write;