feat: add Process.version static method exposing WREN_VERSION_STRING

Implement a new `Process.version` foreign static method that returns the Wren version string. The C implementation uses `wrenSetSlotString` with the `WREN_VERSION_STRING` macro, and the Wren binding registers it alongside existing `Process` methods. A new test file validates the returned value is a non-empty string composed of dot-separated numeric segments.

src/cli/modules.c

@@ -25,6 +25,7 @@ extern void fileWriteBytes(WrenVM* vm);
 extern void platformIsPosix(WrenVM* vm);
 extern void platformName(WrenVM* vm);
 extern void processAllArguments(WrenVM* vm);
+extern void processVersion(WrenVM* vm);
 extern void processCwd(WrenVM* vm);
 extern void statPath(WrenVM* vm);
 extern void statBlockCount(WrenVM* vm);
@@ -166,6 +167,7 @@ static ModuleRegistry modules[] =
     END_CLASS
     CLASS(Process)
       STATIC_METHOD("allArguments", processAllArguments)
+      STATIC_METHOD("version", processVersion)
       STATIC_METHOD("cwd", processCwd)
     END_CLASS
   END_MODULE