feat(simulation): complete interaction and monologue pipelines (#413, #414, #415)

Three fixes to make the gameplay loop functional end-to-end:

- Add Interactable component to NPC spawn so E-prompt detection works
- Build monologue trigger system (enter_location + time_idle) with
  MonologueBuffer/MonologueState components, wire through ObserverSnapshot
  as current_monologue field, decode on client and display via HUD
- Change PlayerAction::Interact from unit to struct variant carrying
  optional target_entity_id and verb fields

Bumps protocol version from 4 to 5. Regenerates MessagePack fixtures.
All 200 tests pass (170 unit + 30 integration).

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

server/src/perception/observer/tests.rs

@@ -2,6 +2,7 @@ use super::*;
 use crate::knowledge::{EntityRegistry, KnowledgeGraph};
 use crate::perception::query::{ActivePerceptionMode, VisibilityGeometry};
 use crate::perception::vision_cone::Facing;
+use crate::simulation::monologue::MonologueBuffer;
 use bevy_ecs::world::World;
 
 /// Helper: set up a test world with resources for the two-stage observer pipeline.
@@ -48,13 +49,14 @@ fn player_always_visible_in_snapshot() {
         Facing::default(),
         KnowledgeGraph::new(),
         NearbyInteractionBuffer::default(),
+        MonologueBuffer::default(),
     ));
 
     run_observer_pipeline(&mut world);
 
     let buffer = world.resource::<SnapshotBuffer>();
     let snapshot = buffer.snapshot.as_ref().expect("snapshot should exist");
-    assert_eq!(snapshot.version, 4);
+    assert_eq!(snapshot.version, 5);
     assert_eq!(snapshot.entities.len(), 1);
     assert!(matches!(snapshot.entities[0].kind, EntityKind::Player));
     assert_eq!(snapshot.entities[0].observation, EntityVisibility::Visible);
@@ -69,6 +71,7 @@ fn npc_in_los_visible() {
         Facing(FacingDirection::North),
         KnowledgeGraph::new(),
         NearbyInteractionBuffer::default(),
+        MonologueBuffer::default(),
     ));
     // NPC directly north of player (in forward cone)
     world.spawn((crate::npc::Npc, TilePosition::new(16, 14, 0)));
@@ -96,6 +99,7 @@ fn npc_behind_wall_not_visible() {
         Facing(FacingDirection::North),
         KnowledgeGraph::new(),
         NearbyInteractionBuffer::default(),
+        MonologueBuffer::default(),
     ));
     // Wall between player and NPC
     let mut walkability = world.resource_mut::<WalkabilityMap>();
@@ -125,6 +129,7 @@ fn npc_behind_player_not_visible() {
         Facing(FacingDirection::North),
         KnowledgeGraph::new(),
         NearbyInteractionBuffer::default(),
+        MonologueBuffer::default(),
     ));
     // NPC far behind player (south, in blind spot)
     world.spawn((crate::npc::Npc, TilePosition::new(16, 26, 0)));
@@ -150,6 +155,7 @@ fn different_z_level_not_visible() {
         Facing::default(),
         KnowledgeGraph::new(),
         NearbyInteractionBuffer::default(),
+        MonologueBuffer::default(),
     ));
     // NPC on different z-level
     world.spawn((crate::npc::Npc, TilePosition::new(16, 14, 1)));
@@ -179,6 +185,7 @@ fn game_time_populated() {
         Facing::default(),
         KnowledgeGraph::new(),
         NearbyInteractionBuffer::default(),
+        MonologueBuffer::default(),
     ));
 
     run_observer_pipeline(&mut world);
@@ -202,6 +209,7 @@ fn visible_tiles_populated() {
         Facing::default(),
         KnowledgeGraph::new(),
         NearbyInteractionBuffer::default(),
+        MonologueBuffer::default(),
     ));
 
     run_observer_pipeline(&mut world);
@@ -241,6 +249,7 @@ fn visible_npc_has_relationship_from_knowledge() {
         Facing(FacingDirection::North),
         kg,
         NearbyInteractionBuffer::default(),
+        MonologueBuffer::default(),
     ));
 
     world.insert_resource(registry);
@@ -283,6 +292,7 @@ fn remembered_entity_appears_as_ghost() {
             Facing(FacingDirection::North),
             kg,
             NearbyInteractionBuffer::default(),
+            MonologueBuffer::default(),
         ))
         .id();
     registry.register(player);
@@ -336,6 +346,7 @@ fn direct_confidence_not_shown_as_remembered() {
             Facing(FacingDirection::North),
             kg,
             NearbyInteractionBuffer::default(),
+            MonologueBuffer::default(),
         ))
         .id();
     registry.register(player);
@@ -386,6 +397,7 @@ fn remembered_entity_on_visible_tile_not_shown() {
             Facing(FacingDirection::North),
             kg,
             NearbyInteractionBuffer::default(),
+            MonologueBuffer::default(),
         ))
         .id();
     registry.register(player);
@@ -430,6 +442,7 @@ fn remembered_entity_different_z_not_shown() {
             Facing(FacingDirection::North),
             kg,
             NearbyInteractionBuffer::default(),
+            MonologueBuffer::default(),
         ))
         .id();
     registry.register(player);
@@ -483,6 +496,7 @@ fn knowledge_without_position_not_shown() {
             Facing(FacingDirection::North),
             kg,
             NearbyInteractionBuffer::default(),
+            MonologueBuffer::default(),
         ))
         .id();
     registry.register(player);
@@ -513,6 +527,7 @@ fn multiple_npcs_in_los_all_visible() {
         Facing(FacingDirection::North),
         KnowledgeGraph::new(),
         NearbyInteractionBuffer::default(),
+        MonologueBuffer::default(),
     ));
     // Three NPCs in front of player, no walls
     world.spawn((crate::npc::Npc, TilePosition::new(16, 14, 0)));
@@ -548,6 +563,7 @@ fn npc_behind_wall_excluded_from_multi_entity_snapshot() {
         Facing(FacingDirection::North),
         KnowledgeGraph::new(),
         NearbyInteractionBuffer::default(),
+        MonologueBuffer::default(),
     ));
     // NPC 1: behind wall (should be hidden)
     world.spawn((crate::npc::Npc, TilePosition::new(16, 13, 0)));
@@ -596,6 +612,7 @@ fn poi_interaction_gets_observe_first_priority() {
             Facing(FacingDirection::North),
             kg,
             NearbyInteractionBuffer::default(),
+            MonologueBuffer::default(),
         ))
         .id();
     registry.register(player);