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/test_world/constants.rs

@@ -255,6 +255,49 @@ pub const SHIFT_CHANGE: GauntletRoom = GauntletRoom {
     reset_plate: Some(TilePosition { x: 72, y: 78, z: 0 }),
 };
 
+/// Zone Gate — Room 15 (16x22)
+/// Tests D-077 zone assignment and zone-crossing detection (#512).
+///
+/// Room is split at x=72 (absolute) into two zones:
+///   Terminal side (x=64-71): ZONE_GATE_TERMINAL_ZONE_ID (zone_id=100)
+///   Corridor side (x=72-79): ZONE_GATE_CORRIDOR_ZONE_ID (zone_id=101)
+///
+/// A door entity sits on the boundary at (72, 112, 0). Moving from the
+/// Terminal side to the Corridor side (or vice versa) fires ZoneCrossEvent.
+///
+/// Observer starts on the Terminal side at (70, 112, 0), facing East.
+pub const ZONE_GATE: GauntletRoom = GauntletRoom {
+    name: "zone_gate",
+    origin: TilePosition {
+        x: 64,
+        y: 102,
+        z: 0,
+    },
+    size: (16, 22),
+    spawn: TilePosition {
+        x: 70,
+        y: 112,
+        z: 0,
+    },
+    observer: TilePosition {
+        x: 70,
+        y: 112,
+        z: 0,
+    },
+    observer_facing: Facing(FacingDirection::East),
+    reset_plate: Some(TilePosition {
+        x: 72,
+        y: 102,
+        z: 0,
+    }),
+};
+
+/// Zone ID for the Terminal (left/west) half of the Zone Gate room.
+pub const ZONE_GATE_TERMINAL_ZONE_ID: u16 = 100;
+
+/// Zone ID for the Corridor (right/east) half of the Zone Gate room.
+pub const ZONE_GATE_CORRIDOR_ZONE_ID: u16 = 101;
+
 /// All rooms in canonical spawn order.
 /// THIS ORDER DETERMINES STABLEID ASSIGNMENT.
 /// Do not reorder existing entries. Append new rooms at the end.
@@ -273,6 +316,7 @@ pub const ROOMS: &[GauntletRoom] = &[
     SOUND_LAB,
     DECAY_OBSERVATORY,
     SHIFT_CHANGE,
+    ZONE_GATE,
 ];
 
 /// Look up which room a position falls in.
@@ -323,6 +367,11 @@ pub const DECAY_OBSERVATORY_STABLE_IDS: (u64, u64) = (69, 69);
 pub const SHIFT_CHANGE_STABLE_IDS: (u64, u64) = (70, 71);
 /// Reset plates for Sprint 13 rooms (sound_lab, decay_observatory, shift_change).
 pub const SPRINT13_RESET_PLATE_STABLE_IDS: (u64, u64) = (72, 74);
+// Sprint 22 rooms — appended after SPRINT13_RESET_PLATE_STABLE_IDS per additive-only rule.
+/// Zone Gate room: door entity at the zone boundary.
+pub const ZONE_GATE_STABLE_IDS: (u64, u64) = (75, 75);
+/// Reset plate for Sprint 22 rooms (zone_gate).
+pub const SPRINT22_RESET_PLATE_STABLE_IDS: (u64, u64) = (76, 76);
 
 /// Number of actively-spawned entities in the current Gauntlet build.
 /// Derived from StableId ranges of all rooms + player + reset plates.
@@ -343,7 +392,9 @@ pub const EXPECTED_ENTITY_COUNT: usize = 1 // player (StableId 0)
     + (SOUND_LAB_STABLE_IDS.1 - SOUND_LAB_STABLE_IDS.0 + 1) as usize
     + (DECAY_OBSERVATORY_STABLE_IDS.1 - DECAY_OBSERVATORY_STABLE_IDS.0 + 1) as usize
     + (SHIFT_CHANGE_STABLE_IDS.1 - SHIFT_CHANGE_STABLE_IDS.0 + 1) as usize
-    + (SPRINT13_RESET_PLATE_STABLE_IDS.1 - SPRINT13_RESET_PLATE_STABLE_IDS.0 + 1) as usize;
+    + (SPRINT13_RESET_PLATE_STABLE_IDS.1 - SPRINT13_RESET_PLATE_STABLE_IDS.0 + 1) as usize
+    + (ZONE_GATE_STABLE_IDS.1 - ZONE_GATE_STABLE_IDS.0 + 1) as usize
+    + (SPRINT22_RESET_PLATE_STABLE_IDS.1 - SPRINT22_RESET_PLATE_STABLE_IDS.0 + 1) as usize;
 
 #[cfg(test)]
 mod tests {
@@ -452,7 +503,7 @@ mod tests {
 
     #[test]
     fn all_rooms_in_correct_order() {
-        assert_eq!(ROOMS.len(), 14);
+        assert_eq!(ROOMS.len(), 15);
         assert_eq!(ROOMS[0].name, "central_hub");
         assert_eq!(ROOMS[1].name, "fog_theater");
         assert_eq!(ROOMS[2].name, "occlusion_corridor");
@@ -467,6 +518,7 @@ mod tests {
         assert_eq!(ROOMS[11].name, "sound_lab");
         assert_eq!(ROOMS[12].name, "decay_observatory");
         assert_eq!(ROOMS[13].name, "shift_change");
+        assert_eq!(ROOMS[14].name, "zone_gate");
     }
 
     #[test]
@@ -533,6 +585,8 @@ mod tests {
             DECAY_OBSERVATORY_STABLE_IDS,
             SHIFT_CHANGE_STABLE_IDS,
             SPRINT13_RESET_PLATE_STABLE_IDS,
+            ZONE_GATE_STABLE_IDS,
+            SPRINT22_RESET_PLATE_STABLE_IDS,
         ];
         for (i, a) in ranges.iter().enumerate() {
             for (j, b) in ranges.iter().enumerate() {