fix(simulation): persist TriangleState in SaveStateV1

Triangle phase and tension were silently lost on save/load. Now
serialized as triangle_states vec in SaveStateV1, sorted by
triangle_id for determinism (D-010). Dedicated triangle entities
are respawned on load.

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

server/src/simulation/save_state.rs

@@ -39,7 +39,7 @@ use bevy_ecs::entity::Entity;
 use bevy_ecs::world::World;
 use serde::{Deserialize, Serialize};
 
-use crate::content::template::{TemplateOwnership, TemplateReferenceMap};
+use crate::content::template::{TemplateOwnership, TemplateReferenceMap, TriangleState};
 use crate::knowledge::graph::KnowledgeGraph;
 use crate::knowledge::registry::StableEntityId;
 use crate::knowledge::types::StableId;
@@ -89,6 +89,11 @@ pub struct SaveStateV1 {
     /// relationship metadata even when their NPCs are not in Active tier.
     #[serde(default)]
     pub template_references: TemplateReferenceMap,
+    /// Triangle escalation states (#250).
+    /// Persisted so tension/phase survive save/load. Sorted by triangle_id
+    /// for deterministic serialization (D-010).
+    #[serde(default)]
+    pub triangle_states: Vec<TriangleState>,
 }
 
 /// Per-NPC state snapshot for `SaveStateV1`.
@@ -399,6 +404,7 @@ mod tests {
             relationship_graph: RelationshipGraph::new(),
             npc_states: vec![],
             template_references: TemplateReferenceMap::default(),
+            triangle_states: vec![],
         }
     }
 
@@ -794,6 +800,7 @@ mod tests {
             relationship_graph: RelationshipGraph::new(),
             npc_states: vec![frozen],
             template_references: TemplateReferenceMap::default(),
+            triangle_states: vec![],
         };
 
         let bytes = save.to_bytes().expect("serialize");