chore(simulation): address review suggestions — comments and minor fixes

- monologue.rs: tracing::warn on unrecognized trigger in fallback arm
- disclosure.rs: borrow-sequencing comment, first() simplification note
- trait_modifiers.rs: delegate parse_confidence to KnowledgeConfidence::try_from
- npc_knowledge_transfer.rs: fix misleading "draw randomly" comment,
  document one-directional transfer behavior
- graph.rs: document intentional no-retrigger after contradiction
- dialogue.rs: explain entity grant guardrail asymmetry (D-079)
- knowledge/mod.rs: document one-tick monologue lag from system ordering
- poi_discovery.rs: document D-079 carve-out for direct KG write

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/npc/disclosure.rs

@@ -293,6 +293,9 @@ pub fn process_unprompted_disclosure(
                 let npc_sid = sid_opt?.0;
 
                 // Gate 2: candidate pool non-empty.
+                // Takes highest-priority candidate (sorted by confidence desc,
+                // then recency desc in derive_disclosure_candidates). Full Layer 4
+                // line selection with variety tracking is deferred to #172.
                 let fact_id = candidates.candidates.first()?.clone();
 
                 // Gate 3: NPC→player trust >= Surface.
@@ -404,6 +407,10 @@ pub fn process_unprompted_disclosure(
     }
 
     // 3. Update NPC cooldown state.
+    // Note: re-queries npc_query mutably after the read pass above. This is
+    // safe because the read pass only borrows shared refs and completes before
+    // this point. The two-phase pattern (read → select winner → write) avoids
+    // holding a mutable borrow during iteration.
     if let Ok((_, _, _, _, _, _, _, mut cooldown)) = npc_query.get_mut(winner.entity) {
         cooldown.per_fact_history.insert(winner.fact_id.clone());
         cooldown.npc_cooldown_until = current_tick + NPC_COOLDOWN_TICKS;

server/src/npc/trait_modifiers.rs

@@ -189,17 +189,12 @@ impl TraitModifierConfig {
 // ---------------------------------------------------------------------------
 
 /// Parse a confidence string from YAML config to enum value.
+/// Delegates to `KnowledgeConfidence::try_from` (which accepts both
+/// camelCase and underscore forms) rather than duplicating the match.
 fn parse_confidence(s: &str) -> Option<KnowledgeConfidence> {
-    match s {
-        "suspects" => Some(KnowledgeConfidence::Suspects),
-        "knows_of" => Some(KnowledgeConfidence::KnowsOf),
-        "knows_details" => Some(KnowledgeConfidence::KnowsDetails),
-        "direct" => Some(KnowledgeConfidence::Direct),
-        _ => {
-            tracing::warn!("Unknown confidence level in trait config: {:?}", s);
-            None
-        }
-    }
+    KnowledgeConfidence::try_from(s).map_err(|e| {
+        tracing::warn!("Unknown confidence level in trait config: {}", e);
+    }).ok()
 }
 
 /// Convert a `PersonalityTrait` to its lowercase YAML key.