fix(simulation): register interaction systems and persist door state (#246)

Follow-up to b6a9b78: register TerminalInteractedQueue resource and
door/terminal interaction systems in SimulationPlugin; add door state
save/load in save_io (open doors round-trip through SaveStateV1);
make WalkabilityMap param optional in process_door_interaction so
plugin-only tests work without a loaded map; fix information_boundaries
test missing open_doors field.

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

server/src/simulation/interaction.rs

@@ -407,7 +407,7 @@ pub struct TerminalInteractRequest {
 /// Ordering: after `process_player_input`, before movement validation.
 pub fn process_door_interaction(
     mut commands: Commands,
-    mut walkability: ResMut<WalkabilityMap>,
+    walkability: Option<ResMut<WalkabilityMap>>,
     player_query: Query<(Entity, &DoorInteractRequest), With<PlayerCharacter>>,
     mut door_query: Query<&mut DoorState>,
 ) {
@@ -428,7 +428,9 @@ pub fn process_door_interaction(
     let walkable = door.is_open;
     let tile = door.blocking_tile;
 
-    walkability.set_walkable(&tile, walkable);
+    if let Some(mut walkability) = walkability {
+        walkability.set_walkable(&tile, walkable);
+    }
 
     tracing::info!(
         ?tile,