feat(simulation): add Zone Gate gauntlet room and zone crossing detection (#512)

New test_world room with two zones (Terminal/Corridor) separated by
a door. Adds ZoneCrossEventQueue resource and detect_zone_crossings
system to fire events when the player crosses zone boundaries.

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

server/src/simulation/mod.rs

@@ -9,10 +9,12 @@ pub mod conversation;
 pub mod dialogue;
 pub mod examine;
 pub mod follow;
+pub mod generator;
 pub mod input;
 pub mod interaction;
 pub mod inventory;
 pub mod listening;
+pub mod modification;
 pub mod monologue;
 pub mod movement;
 pub mod npc_knowledge_transfer;
@@ -63,6 +65,9 @@ impl Plugin for SimulationPlugin {
             .init_resource::<crate::npc::relationships::RelationshipGraph>()
             .init_resource::<crate::knowledge::KnowledgeEventQueue>()
             .init_resource::<interaction::TerminalInteractedQueue>()
+            // Zone crossing event queue (#512, D-077): detect when player moves between zones.
+            .init_resource::<zone::ZoneCrossEventQueue>()
+            .init_resource::<zone::PreviousPlayerZone>()
             .add_systems(
                 Update,
                 (
@@ -116,6 +121,12 @@ impl Plugin for SimulationPlugin {
                         .before(crate::perception::observer::compute_observer_snapshot),
                     time::advance_tick.after(path_follow::cleanup_path_blocked),
                 ),
+            )
+            // Zone crossing detection (#512, D-077) — separate call to stay within
+            // Bevy's 20-element system tuple limit.
+            .add_systems(
+                Update,
+                zone::detect_zone_crossings.after(movement::validate_movement),
             );
 
         tracing::debug!("SimulationPlugin initialized");