[playground] Downgrade Next.js to a secure version (facebook#35317)

Was bumped to a canary in facebook#34499
which got never released as stable.

Presumeably to use `Activity` which only made it into Activity in later
Next.js releases. However, `Activity` never ended up being used due to
incompatibilities with Monaco Editor. Downgrading should be safe.

Downgrading to fix
GHSA-9qr9-h5gf-34mp.
This will allow new deploys since Vercel is currently blocking new
deploys of unsafe version

---------

Co-authored-by: Eugene Choi <4eugenechoi@gmail.com>

DiffTrain build for [55480b4](facebook@55480b4)

Author: surajmaity1

compiled-rn/VERSION_NATIVE_FB

@@ -1 +1 @@
-19.2.0-native-fb-4082b0e7-20250828
+19.3.0-native-fb-55480b4d-20251208

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react/react-dom/cjs/ReactDOM-dev.js

@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<4175c435d44f4319000cb9436906673a>>
+ * @generated SignedSource<<80f6df819ea1540d856fbb7252571d0f>>
  */
 
 "use strict";
@@ -20,25 +20,30 @@ __DEV__ &&
     function createPortal$1(children, containerInfo, implementation) {
       var key =
         3 < arguments.length && void 0 !== arguments[3] ? arguments[3] : null;
-      try {
-        testStringCoercion(key);
-        var JSCompiler_inline_result = !1;
-      } catch (e) {
-        JSCompiler_inline_result = !0;
+      if (null == key) key = null;
+      else if (key === REACT_OPTIMISTIC_KEY) key = REACT_OPTIMISTIC_KEY;
+      else {
+        try {
+          testStringCoercion(key);
+          var JSCompiler_inline_result = !1;
+        } catch (e) {
+          JSCompiler_inline_result = !0;
+        }
+        JSCompiler_inline_result &&
+          (console.error(
+            "The provided key is an unsupported type %s. This value must be coerced to a string before using it here.",
+            ("function" === typeof Symbol &&
+              Symbol.toStringTag &&
+              key[Symbol.toStringTag]) ||
+              key.constructor.name ||
+              "Object"
+          ),
+          testStringCoercion(key));
+        key = "" + key;
       }
-      JSCompiler_inline_result &&
-        (console.error(
-          "The provided key is an unsupported type %s. This value must be coerced to a string before using it here.",
-          ("function" === typeof Symbol &&
-            Symbol.toStringTag &&
-            key[Symbol.toStringTag]) ||
-            key.constructor.name ||
-            "Object"
-        ),
-        testStringCoercion(key));
       return {
         $$typeof: REACT_PORTAL_TYPE,
-        key: null == key ? null : "" + key,
+        key: key,
         children: children,
         containerInfo: containerInfo,
         implementation: implementation
@@ -100,6 +105,7 @@ __DEV__ &&
         findDOMNode: null
       },
       REACT_PORTAL_TYPE = Symbol.for("react.portal"),
+      REACT_OPTIMISTIC_KEY = Symbol.for("react.optimistic_key"),
       ReactSharedInternals =
         React.__CLIENT_INTERNALS_DO_NOT_USE_OR_WARN_USERS_THEY_CANNOT_UPGRADE;
     ("function" === typeof Map &&
@@ -404,5 +410,5 @@ __DEV__ &&
     exports.useFormStatus = function () {
       return resolveDispatcher().useHostTransitionStatus();
     };
-    exports.version = "19.2.0-native-fb-4082b0e7-20250828";
+    exports.version = "19.3.0-native-fb-55480b4d-20251208";
   })();

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react/react-dom/cjs/ReactDOM-prod.js

@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<5d8d1e06786393aa6dee0f4c366443e2>>
+ * @generated SignedSource<<b33265c8ad767902ad17a243a8c46df5>>
  */
 
 "use strict";
@@ -45,13 +45,19 @@ var Internals = {
     p: 0,
     findDOMNode: null
   },
-  REACT_PORTAL_TYPE = Symbol.for("react.portal");
+  REACT_PORTAL_TYPE = Symbol.for("react.portal"),
+  REACT_OPTIMISTIC_KEY = Symbol.for("react.optimistic_key");
 function createPortal$1(children, containerInfo, implementation) {
   var key =
     3 < arguments.length && void 0 !== arguments[3] ? arguments[3] : null;
   return {
     $$typeof: REACT_PORTAL_TYPE,
-    key: null == key ? null : "" + key,
+    key:
+      null == key
+        ? null
+        : key === REACT_OPTIMISTIC_KEY
+          ? REACT_OPTIMISTIC_KEY
+          : "" + key,
     children: children,
     containerInfo: containerInfo,
     implementation: implementation
@@ -203,4 +209,4 @@ exports.useFormState = function (action, initialState, permalink) {
 exports.useFormStatus = function () {
   return ReactSharedInternals.H.useHostTransitionStatus();
 };
-exports.version = "19.2.0-native-fb-4082b0e7-20250828";
+exports.version = "19.3.0-native-fb-55480b4d-20251208";

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react/react-dom/cjs/ReactDOM-profiling.js

@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<5d8d1e06786393aa6dee0f4c366443e2>>
+ * @generated SignedSource<<b33265c8ad767902ad17a243a8c46df5>>
  */
 
 "use strict";
@@ -45,13 +45,19 @@ var Internals = {
     p: 0,
     findDOMNode: null
   },
-  REACT_PORTAL_TYPE = Symbol.for("react.portal");
+  REACT_PORTAL_TYPE = Symbol.for("react.portal"),
+  REACT_OPTIMISTIC_KEY = Symbol.for("react.optimistic_key");
 function createPortal$1(children, containerInfo, implementation) {
   var key =
     3 < arguments.length && void 0 !== arguments[3] ? arguments[3] : null;
   return {
     $$typeof: REACT_PORTAL_TYPE,
-    key: null == key ? null : "" + key,
+    key:
+      null == key
+        ? null
+        : key === REACT_OPTIMISTIC_KEY
+          ? REACT_OPTIMISTIC_KEY
+          : "" + key,
     children: children,
     containerInfo: containerInfo,
     implementation: implementation
@@ -203,4 +209,4 @@ exports.useFormState = function (action, initialState, permalink) {
 exports.useFormStatus = function () {
   return ReactSharedInternals.H.useHostTransitionStatus();
 };
-exports.version = "19.2.0-native-fb-4082b0e7-20250828";
+exports.version = "19.3.0-native-fb-55480b4d-20251208";