Convert store and CLI to anyhow::Result for cleaner error handling

Replace Result<_, String> with anyhow::Result throughout:
- hippocampus/store module (persist, ops, types, view, mod)
- CLI modules (admin, agent, graph, journal, node)
- Run trait in main.rs

Use .context() and .with_context() instead of .map_err(|e| format!(...))
patterns. Add bail!() for early error returns.

Add access_local() helper in hippocampus/mod.rs that returns
Result<Arc<Mutex<Store>>> for direct local store access.

Fix store access patterns to properly lock Arc<Mutex<Store>> before
accessing fields in mind/unconscious.rs, mind/mod.rs, subconscious/learn.rs,
and hippocampus/memory.rs.

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

src/mind/mod.rs

@@ -26,6 +26,7 @@ use crate::agent::{Agent, TurnResult};
 use crate::agent::api::ApiClient;
 use crate::config::{AppConfig, SessionConfig};
 use crate::subconscious::learn;
+use crate::hippocampus::access_local;
 
 pub use subconscious::{SubconsciousSnapshot, Subconscious};
 pub use unconscious::{UnconsciousSnapshot, Unconscious};
@@ -349,8 +350,10 @@ impl Mind {
                         // Phase 0: health check outside lock (slow I/O)
                         let needs_health = unc.lock().await.needs_health_refresh();
                         if needs_health {
-                            if let Ok(store) = crate::store::Store::load() {
+                            if let Ok(store_arc) = access_local() {
+                                let store = store_arc.lock().await;
                                 let health = crate::subconscious::daemon::compute_graph_health(&store);
+                                drop(store);
                                 unc.lock().await.set_health(health);
                             }
                         }