feat(simulation): sprint 9 gauntlet — test infrastructure and first 3 rooms

Add Gauntlet test world with 3 rooms (Inventory Warehouse, Occlusion
Corridor, Pause Chamber) + Central Hub, room constants module, room
reset trigger mechanism, Layer 3 subprocess integration test, golden
file comparison engine and test suite, and content runtime validation.

Tickets: #482, #484, #485, #487, #488, #489, #490

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

server/Cargo.lock

@@ -950,6 +950,19 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "serde_json"
+version = "1.0.149"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "83fc039473c5595ace860d8c4fafa220ff474b3fc6bfdb4293327f1a37e94d86"
+dependencies = [
+ "itoa",
+ "memchr",
+ "serde",
+ "serde_core",
+ "zmij",
+]
+
 [[package]]
 name = "serde_yaml"
 version = "0.9.34+deprecated"
@@ -975,6 +988,7 @@ dependencies = [
  "rand_chacha",
  "rmp-serde",
  "serde",
+ "serde_json",
  "serde_yaml",
  "thiserror",
  "tracing",
@@ -1373,3 +1387,9 @@ dependencies = [
  "quote",
  "syn",
 ]
+
+[[package]]
+name = "zmij"
+version = "1.0.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b8848ee67ecc8aedbaf3e4122217aff892639231befc6a1b58d29fff4c2cabaa"