feat: add File.realPath() to resolve symlinks and normalize paths

Implement a new static method `File.realPath(path)` that resolves the given path by traversing symlinks and removing redundant `./` and `../` components, returning the canonical absolute path. The implementation uses libuv's `uv_fs_realpath` via an asynchronous callback pattern consistent with other File operations. Includes documentation, foreign method declarations, and two error-case tests for nonexistent paths and wrong argument types.

src/module/io.c

@@ -302,6 +302,23 @@ void fileReadBytes(WrenVM* vm)
              fileReadBytesCallback);
 }
 
+static void realPathCallback(uv_fs_t* request)
+{
+  if (handleRequestError(request)) return;
+  
+  wrenEnsureSlots(getVM(), 3);
+  wrenSetSlotString(getVM(), 2, (char*)request->ptr);
+  schedulerResume(freeRequest(request), true);
+  schedulerFinishResume();
+}
+
+void fileRealPath(WrenVM* vm)
+{
+  const char* path = wrenGetSlotString(vm, 1);
+  uv_fs_t* request = createRequest(wrenGetSlotValue(vm, 2));
+  uv_fs_realpath(getLoop(), request, path, realPathCallback);
+}
+
 // Called by libuv when the stat call completes.
 static void statCallback(uv_fs_t* request)
 {

src/module/io.wren

@@ -91,6 +91,14 @@ foreign class File {
     return File.open(path) {|file| file.readBytes(file.size) }
   }
 
+  // TODO: This works for directories too, so putting it on File is kind of
+  // lame. Consider reorganizing these classes some.
+  static realPath(path) {
+    ensurePath_(path)
+    realPath_(path, Fiber.current)
+    return Scheduler.runNextScheduled_()
+  }
+
   static size(path) {
     ensurePath_(path)
     sizePath_(path, Fiber.current)
@@ -158,6 +166,7 @@ foreign class File {
 
   foreign static delete_(path, fiber)
   foreign static open_(path, flags, fiber)
+  foreign static realPath_(path, fiber)
   foreign static sizePath_(path, fiber)
 
   foreign close_(fiber)

src/module/io.wren.inc

@@ -93,6 +93,14 @@ static const char* ioModuleSource =
 "    return File.open(path) {|file| file.readBytes(file.size) }\n"
 "  }\n"
 "\n"
+"  // TODO: This works for directories too, so putting it on File is kind of\n"
+"  // lame. Consider reorganizing these classes some.\n"
+"  static realPath(path) {\n"
+"    ensurePath_(path)\n"
+"    realPath_(path, Fiber.current)\n"
+"    return Scheduler.runNextScheduled_()\n"
+"  }\n"
+"\n"
 "  static size(path) {\n"
 "    ensurePath_(path)\n"
 "    sizePath_(path, Fiber.current)\n"
@@ -160,6 +168,7 @@ static const char* ioModuleSource =
 "\n"
 "  foreign static delete_(path, fiber)\n"
 "  foreign static open_(path, flags, fiber)\n"
+"  foreign static realPath_(path, fiber)\n"
 "  foreign static sizePath_(path, fiber)\n"
 "\n"
 "  foreign close_(fiber)\n"