Introduce ActionValidationStatus enum (valid, unresolved, missing_argument,
invalid_argument, ambiguous_target) as the typed classification of validation
outcomes. ActionValidationResult now carries Status instead of boolean flags.
Backward-compatible: Unresolved() and Valid() methods preserved on the result.
Existing validation behavior unchanged: only blank Fn produces invalid_argument.
All downstream behavior (proposeGap, confirmation, task_status, praxis, hexis)
unchanged.
Tests added for all five status values, backward compatibility, and the full
validation → execution boundary.
claude
66c578a6f4