Fix codegen crashes for intersection types and complex list inner types

[daweifeng-replit]

Why

Codegen fails when a schema contains intersection types (allOf) or lists with complex inner types (e.g. list[dict[str, Any]]). Both crash with Complex type must be put through render_type_expr! or Unexpected expression when expecting a type name: DictTypeExpr(...) because TypeName objects are used directly in f-strings or passed to ensure_literal_type which only accepts simple TypeName values.

What changed

• Fix TypeName.__str__() crash in the RiverIntersectionType encoder by wrapping encoder_name with render_literal_type(), matching the existing pattern used by RiverUnionType (line 625) and RiverConcreteType (line 654)
• Fix ensure_literal_type crash when a list's inner type is a complex expression (e.g. list[dict[str, Any]]) by guarding the ListTypeExpr match to only enter the encoding branch for TypeName inner types, falling through to list(x) for composite types that don't need encoding

Test plan

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