feat(simulation): wire Sprint 15 systems + protocol v13

Register all new systems in NpcPlugin and SimulationPlugin with correct
ordering constraints. Protocol bumped to v13: tell_state on VisibleEntity,
follow_state and PostConversationQueue on ObserverSnapshot, Follow verb
on VerbKind. Observer snapshot populates tell state from DerivedTellState
and follow state from FollowTarget. System ordering: tolerance after
mood, deviation after activity, tell after mood+deviation, follow after
visibility geometry, event monologue after conversations.

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

server/src/simulation/mod.rs

@@ -7,6 +7,7 @@ use bevy_ecs::schedule::IntoScheduleConfigs;
 pub mod contraband;
 pub mod conversation;
 pub mod dialogue;
+pub mod follow;
 pub mod input;
 pub mod interaction;
 pub mod inventory;
@@ -17,6 +18,7 @@ pub mod path_follow;
 pub mod pathfinding;
 pub mod rng;
 pub mod sound;
+pub mod spatial;
 pub mod stance;
 pub mod tier;
 pub mod time;
@@ -37,6 +39,9 @@ impl Plugin for SimulationPlugin {
             .init_resource::<input::InputQueue>()
             .init_resource::<crate::knowledge::EntityRegistry>()
             .init_resource::<sound::SoundEventQueue>()
+            .init_resource::<spatial::NaiveSpatialIndex>()
+            .init_resource::<follow::FollowEndEventQueue>()
+            .init_resource::<monologue::PostConversationQueue>()
             .add_systems(
                 Update,
                 (
@@ -45,6 +50,7 @@ impl Plugin for SimulationPlugin {
                     path_follow::follow_paths.after(pathfinding::compute_paths),
                     movement::validate_movement.after(path_follow::follow_paths),
                     path_follow::cleanup_path_blocked.after(movement::validate_movement),
+                    spatial::sync_spatial_index.after(movement::validate_movement),
                     listening::update_listening_focus.after(movement::validate_movement),
                     contraband::check_contraband_scan
                         .after(movement::validate_movement)