feat: Implement state persistence by serializing game and user data to state.json using serde_json.

Cargo.lock

@@ -112,6 +112,8 @@ dependencies = [
  "prost-types",
  "rocket",
  "rocket_prost_responder_derive",
+ "serde",
+ "serde_json",
  "uuid",
 ]
 
@@ -2041,9 +2043,9 @@ checksum = "6d49784317cd0d1ee7ec5c716dd598ec5b4483ea832a2dced265471cc0f690ae"
 
 [[package]]
 name = "uuid"
-version = "1.18.1"
+version = "1.19.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2f87b8aa10b915a06587d0dec516c282ff295b475d94abf425d62b57710070a2"
+checksum = "e2e054861b4bd027cd373e18e8d8d8e6548085000e41290d95ce0c373a654b4a"
 dependencies = [
  "getrandom 0.3.4",
  "js-sys",