This TDD test captures the buggy behavior where `NamespacedName.validate_namespace()`
and `validate_name()` accept names starting with digits, violating the spec requirement
that namespace and name components must start with a letter (consistent with
`_BARE_NAME_RE` in project.py).
Three failing scenarios demonstrate the bug:
1. parse() accepting namespace starting with digit ("123abc/my-action")
2. constructor accepting name starting with digit (local/"123-action")
3. constructor accepting namespace starting with digit ("999org"/valid-name)
Tagged with @tdd_expected_fail per Bug Fix Workflow.
Implements #2145
Blocks #2147
