DJLS Ruff AST

Use this before editing djls-extraction or code that consumes Ruff Python AST nodes.

Known API shapes

• Parse modules with ruff_python_parser::parse_module(source) and call .into_syntax() for ModModule AST.
• Function defaults are per-parameter. There is no top-level defaults field.
  • Use ParameterWithDefault { parameter, default: Option<Box<Expr>> }.
• StmtWhile.test, StmtIf.test, and similar fields are Box<Expr>.
  • Dereference with &* for pattern matching.
• FStringValue uses .iter(), not .parts(), for FStringPart iteration.
• ExceptHandler::ExceptHandler is irrefutable.
  • Use let, not if let.