Add "auto" class to mean the built-in should run (#32761)

Stacked on #32734

In React a ViewTransition class of `"none"` doesn't just mean that it
has no class but also that it has no ViewTransition name. The default
(`null | undefined`) means that it has no specific class but should run
with the default built-in animation. This adds this as an explicit
string called `"auto"` as well.

That way you can do `<ViewTransition default="foo" enter="auto">` to
override the "foo" just for the "enter" trigger to be the default
built-in animation. Where as if you just specified `null` it would be
like not specifying enter at all which would trigger "foo".

DiffTrain build for [fceb0f8](fceb0f8)

Author: poteto

compiled/facebook-www/REVISION

@@ -1 +1 @@
-e0c99c4ea1cae566ad8040180cf180ae058cb8bf
+fceb0f80bc729d061bcb5031801cfc824adc07a9

compiled/facebook-www/REVISION_TRANSFORMS

@@ -1 +1 @@
-e0c99c4ea1cae566ad8040180cf180ae058cb8bf
+fceb0f80bc729d061bcb5031801cfc824adc07a9

compiled/facebook-www/React-dev.classic.js

@@ -1511,7 +1511,7 @@ __DEV__ &&
     exports.useTransition = function () {
       return resolveDispatcher().useTransition();
     };
-    exports.version = "19.1.0-www-classic-e0c99c4e-20250326";
+    exports.version = "19.1.0-www-classic-fceb0f80-20250326";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled/facebook-www/React-dev.modern.js

@@ -1511,7 +1511,7 @@ __DEV__ &&
     exports.useTransition = function () {
       return resolveDispatcher().useTransition();
     };
-    exports.version = "19.1.0-www-modern-e0c99c4e-20250326";
+    exports.version = "19.1.0-www-modern-fceb0f80-20250326";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled/facebook-www/React-prod.classic.js

@@ -624,4 +624,4 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.1.0-www-classic-e0c99c4e-20250326";
+exports.version = "19.1.0-www-classic-fceb0f80-20250326";

compiled/facebook-www/React-prod.modern.js

@@ -624,4 +624,4 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.1.0-www-modern-e0c99c4e-20250326";
+exports.version = "19.1.0-www-modern-fceb0f80-20250326";

compiled/facebook-www/React-profiling.classic.js

@@ -628,7 +628,7 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.1.0-www-classic-e0c99c4e-20250326";
+exports.version = "19.1.0-www-classic-fceb0f80-20250326";
 "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
   "function" ===
     typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled/facebook-www/React-profiling.modern.js

@@ -628,7 +628,7 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.1.0-www-modern-e0c99c4e-20250326";
+exports.version = "19.1.0-www-modern-fceb0f80-20250326";
 "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
   "function" ===
     typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled/facebook-www/ReactART-dev.classic.js

@@ -1974,7 +1974,13 @@ __DEV__ &&
     function getViewTransitionClassName(defaultClass, eventClass) {
       defaultClass = getClassNameByType(defaultClass);
       eventClass = getClassNameByType(eventClass);
-      return null == eventClass ? defaultClass : eventClass;
+      return null == eventClass
+        ? "auto" === defaultClass
+          ? null
+          : defaultClass
+        : "auto" === eventClass
+          ? null
+          : eventClass;
     }
     function is(x, y) {
       return (x === y && (0 !== x || 1 / x === 1 / y)) || (x !== x && y !== y);
@@ -18188,10 +18194,10 @@ __DEV__ &&
     (function () {
       var internals = {
         bundleType: 1,
-        version: "19.1.0-www-classic-e0c99c4e-20250326",
+        version: "19.1.0-www-classic-fceb0f80-20250326",
         rendererPackageName: "react-art",
         currentDispatcherRef: ReactSharedInternals,
-        reconcilerVersion: "19.1.0-www-classic-e0c99c4e-20250326"
+        reconcilerVersion: "19.1.0-www-classic-fceb0f80-20250326"
       };
       internals.overrideHookState = overrideHookState;
       internals.overrideHookStateDeletePath = overrideHookStateDeletePath;
@@ -18225,7 +18231,7 @@ __DEV__ &&
     exports.Shape = Shape;
     exports.Surface = Surface;
     exports.Text = Text;
-    exports.version = "19.1.0-www-classic-e0c99c4e-20250326";
+    exports.version = "19.1.0-www-classic-fceb0f80-20250326";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled/facebook-www/ReactART-dev.modern.js

@@ -1880,7 +1880,13 @@ __DEV__ &&
     function getViewTransitionClassName(defaultClass, eventClass) {
       defaultClass = getClassNameByType(defaultClass);
       eventClass = getClassNameByType(eventClass);
-      return null == eventClass ? defaultClass : eventClass;
+      return null == eventClass
+        ? "auto" === defaultClass
+          ? null
+          : defaultClass
+        : "auto" === eventClass
+          ? null
+          : eventClass;
     }
     function is(x, y) {
       return (x === y && (0 !== x || 1 / x === 1 / y)) || (x !== x && y !== y);
@@ -17960,10 +17966,10 @@ __DEV__ &&
     (function () {
       var internals = {
         bundleType: 1,
-        version: "19.1.0-www-modern-e0c99c4e-20250326",
+        version: "19.1.0-www-modern-fceb0f80-20250326",
         rendererPackageName: "react-art",
         currentDispatcherRef: ReactSharedInternals,
-        reconcilerVersion: "19.1.0-www-modern-e0c99c4e-20250326"
+        reconcilerVersion: "19.1.0-www-modern-fceb0f80-20250326"
       };
       internals.overrideHookState = overrideHookState;
       internals.overrideHookStateDeletePath = overrideHookStateDeletePath;
@@ -17997,7 +18003,7 @@ __DEV__ &&
     exports.Shape = Shape;
     exports.Surface = Surface;
     exports.Text = Text;
-    exports.version = "19.1.0-www-modern-e0c99c4e-20250326";
+    exports.version = "19.1.0-www-modern-fceb0f80-20250326";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&