Memory scores on entries, not a separate Vec

ConversationEntry::Memory gains score: Option<f64>. The scorer
writes scores directly onto entries when results arrive. Removes
Agent.memory_scores Vec and the memory_scores parameter from
context_state_summary().

Scores are serialized to/from the conversation log as memory_score.

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

src/user/context.rs

@@ -29,7 +29,7 @@ impl ConsciousScreen {
 
     fn read_context_state(&self) -> Vec<ContextSection> {
         match self.agent.try_lock() {
-            Ok(ag) => ag.context_state_summary(None),
+            Ok(ag) => ag.context_state_summary(),
             Err(_) => Vec::new(),
         }
     }