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/tests/information_boundaries.rs

@@ -205,6 +205,7 @@ fn save_state_npc_kg_isolation() {
         npc_states: vec![npc_a_state, npc_b_state],
         template_references: Default::default(),
         triangle_states: vec![],
+        open_doors: vec![],
     };
 
     // Roundtrip: serialize → deserialize.