Fix codegen for non-discriminated anyOf unions with mixed types

[daweifeng-replit]

Why

The encoder generation for TypedDict inputs produces malformed Python code when handling anyOf unions containing mixed types like [object, string, array].

Before

 return (
     encode_...AnyOf_0(x)
     x
      if isinstance(x, str) else
     encode_str(x)
 )

After

  return (
      encode_...AnyOf_0(x) if isinstance(x, dict) else
      x if isinstance(x, str) else
      list(x)
  )

What changed

• Collect (type_check, encoder_expr) pairs for each union member
• Build a proper ternary chain with isinstance checks
• Handle primitive array items by returning list(x) instead of undefined encoder calls

Test plan

CI