feat(simulation): dialogue pipeline, ContentSlug, and walk-away KG recording

Implement full dialogue selection pipeline (D-028): 4-layer filtering
engine with access tier, situation derivation, trust tier, and weighted
topic+mood scoring via SimRng. Add ContentSlug component for stable
content identity across save/load. Add walk-away KG recording with
IncompleteInteraction events per D-064 three-phase consequences. Bump
protocol to v8 with DialogueResponseEvent. Fixes #305, #427, #452.

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

server/src/knowledge/graph.rs

@@ -145,6 +145,61 @@ impl KnowledgeGraph {
         }
     }
 
+    /// Record an incomplete interaction with an entity (D-064 walk-away).
+    ///
+    /// Appends to known_attributes["incomplete_interactions"] as a
+    /// comma-separated list of "tick:type" entries. Creates the entity
+    /// entry if it doesn't exist (at Suspects confidence).
+    pub fn record_incomplete_interaction(
+        &mut self,
+        target: &StableId,
+        interaction_type: super::events::InteractionType,
+        tick: u64,
+    ) {
+        let entry = self
+            .entities
+            .entry(*target)
+            .or_insert_with(|| EntityKnowledge {
+                last_known_position: None,
+                last_observed_tick: 0,
+                last_updated_tick: 0,
+                confidence: KnowledgeConfidence::Suspects,
+                source: KnowledgeSource::DirectObservation { tick },
+                state: KnowledgeState::Active,
+                relationship: RelationshipState::Unknown,
+                known_attributes: BTreeMap::new(),
+            });
+
+        let type_str = match interaction_type {
+            super::events::InteractionType::Talk => "talk",
+            super::events::InteractionType::Confront => "confront",
+        };
+        let record = format!("{}:{}", tick, type_str);
+
+        entry
+            .known_attributes
+            .entry("incomplete_interactions".to_string())
+            .and_modify(|v| {
+                v.push(',');
+                v.push_str(&record);
+            })
+            .or_insert(record);
+
+        entry.last_updated_tick = tick;
+    }
+
+    /// Check if the observer has any incomplete interactions with an entity.
+    ///
+    /// Returns true if known_attributes["incomplete_interactions"] exists
+    /// and is non-empty. Used by dialogue/monologue systems to gate
+    /// post-conversation reactions (D-064 phase 3).
+    pub fn has_incomplete_interaction(&self, target: &StableId) -> bool {
+        self.entities
+            .get(target)
+            .and_then(|e| e.known_attributes.get("incomplete_interactions"))
+            .is_some_and(|v| !v.is_empty())
+    }
+
     /// Set relationship state for an entity.
     pub fn set_relationship(&mut self, target: &StableId, state: RelationshipState) {
         if let Some(entry) = self.entities.get_mut(target) {