store: remove visit tracking infrastructure

Remove AgentVisit, TranscriptSegment, and all related visit tracking code.
Provenance is what we've been using to track agent interaction with nodes.

Also removes dead fields from Node (state_tag, created).

-349 lines.

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

src/mind/unconscious.rs

@@ -12,7 +12,6 @@ use futures::FutureExt;
 use crate::agent::oneshot::{AutoAgent, AutoStep, RunStats};
 use crate::agent::tools;
 use crate::subconscious::defs;
-use crate::hippocampus::access_local;
 
 fn config_path() -> std::path::PathBuf {
     dirs::home_dir().unwrap_or_default()
@@ -254,12 +253,6 @@ pub async fn prepare_spawn(name: &str, mut auto: AutoAgent) -> Result<SpawnResul
         None => return Err(auto),
     };
 
-    // Run query and resolve placeholders
-    let store_arc = match access_local() {
-        Ok(s) => s,
-        Err(_) => return Err(auto),
-    };
-
     let exclude: std::collections::HashSet<String> = std::collections::HashSet::new();
     let batch = match defs::run_agent(
         &def, def.count.unwrap_or(5), &exclude,
@@ -271,11 +264,6 @@ pub async fn prepare_spawn(name: &str, mut auto: AutoAgent) -> Result<SpawnResul
         }
     };
 
-    if !batch.node_keys.is_empty() {
-        let mut store = store_arc.lock().await;
-        store.record_agent_visits(&batch.node_keys, name).ok();
-    }
-
     let orig_steps = std::mem::replace(&mut auto.steps,
         batch.steps.iter().map(|s| AutoStep {
             prompt: s.prompt.clone(),