feat: add MAX_VARIABLE_NAME limit and improve field overflow error message

Add a 64-character maximum identifier length with compile-time error reporting, and enhance the runtime field overflow error to include the class name and remove the TODO comment. Update test expectations for both limit scenarios.

test/limit/long_variable_name.wren

@@ -0,0 +1,2 @@
+var i234567890i234567890i234567890i234567890i234567890i234 = "value"
+class c234567890c234567890c234567890c234567890c234567890c234567890c234 {}

test/limit/many_inherited_fields.wren

@@ -136,7 +136,7 @@ class Foo {
   }
 }
 
-class Bar is Foo { // expect runtime error: A class may not have more than 255 fields, including inherited ones.
+class Bar is Foo {
   new {
     super
     _field129 = 129
@@ -266,15 +266,16 @@ class Bar is Foo { // expect runtime error: A class may not have more than 255 f
     _field253 = 253
     _field254 = 254
     _field255 = 255
-    _field256 = 256
   }
 
   bar {
     IO.print(_field129)
-    IO.print(_field256)
+    IO.print(_field255)
   }
 }
 
 var bar = new Bar
-bar.foo
-bar.bar
+bar.foo // expect: 1
+// expect: 128
+bar.bar // expect: 129
+// expect: 255

test/limit/too_many_inherited_fields.wren

@@ -136,7 +136,7 @@ class Foo {
   }
 }
 
-class Bar is Foo {
+class Bar is Foo { // expect runtime error: Class 'Bar' may not have more than 255 fields, including inherited ones.
   new {
     super
     _field129 = 129
@@ -266,16 +266,15 @@ class Bar is Foo {
     _field253 = 253
     _field254 = 254
     _field255 = 255
+    _field256 = 256
   }
 
   bar {
     IO.print(_field129)
-    IO.print(_field255)
+    IO.print(_field256)
   }
 }
 
 var bar = new Bar
-bar.foo // expect: 1
-// expect: 128
-bar.bar // expect: 129
-// expect: 255
+bar.foo
+bar.bar

test/limit/variable_name_too_long.wren

@@ -0,0 +1,2 @@
+var i234567890i234567890i234567890i234567890i234567890i2345 = "value" // expect error
+class c234567890c234567890c234567890c234567890c234567890c234567890c2345 {} // expect error