feat: add recursive fibonacci benchmark scripts in lua, python, wren and implicit fields design doc

Add three language implementations of a naive recursive fibonacci(35) benchmark
alongside a design document exploring implicit field declaration semantics for
the wren language, including nested class scoping and static field conventions.

benchmark/fib.lua

@@ -0,0 +1,6 @@
+function fib(n)
+  if n < 2 then return n end
+  return fib(n - 2) + fib(n - 1)
+end
+
+io.write(fib(35) .. "\n")

benchmark/fib.py

@@ -0,0 +1,5 @@
+def fib(n):
+  if n < 2: return n
+  return fib(n - 1) + fib(n - 2)
+
+print fib(35)

benchmark/fib.wren

@@ -0,0 +1,9 @@
+var fib = fn(n) {
+  if (n < 2) {
+    n
+  } else {
+    fib.call(n - 1) + fib.call(n - 2)
+  }
+}
+
+io.write(fib.call(35))