Prevent CAIT __getattr__ recursion crash in Pyodide when astNode is unavailable

[Copilot]

CAIT usage in Pyodide could trigger a fatal runtime error (Maximum call stack size exceeded) from recursive attribute fallback in CaitNode.__getattr__. This surfaced on CAIT operations like prevent_operation("*") when astNode access failed and re-entered __getattr__ indefinitely.

• Root-cause hardening in CaitNode.__getattr__

  • Replaced recursive self.astNode resolution with direct object.__getattribute__(self, "astNode").
  • Converted missing/invalid astNode cases into an immediate AttributeError instead of re-entering __getattr__.

• Error behavior cleanup

  • Standardized the missing-attribute path to raise a descriptive AttributeError for the requested attribute.

• Regression coverage

  • Added a CAIT node test that deletes astNode and asserts attribute access raises AttributeError (no recursion path).

try:
    ast_node = object.__getattribute__(self, "astNode")
except AttributeError:
    raise AttributeError(f"{type(self).__name__} has no attribute {item!r}")