hrw4u: Fix u4wrh emitting quoted header names in Prism output

[Clendenin]

Summary

Header qualifiers that contain only characters legal in the Prism IDENT rule
were being wrapped in double quotes at emission time, which the grammar rejects
on re-parse. Quote a qualifier only when it actually contains characters that
require quoting.

Adds a parametrized unit test for Validator.unquote_if_ident covering
IDENT-safe stripping, space-containing qualifiers, empty strings, and
leading-digit rejection, symmetric with the existing needs_quotes and
quote_if_needed tests.

[Copilot]

Pull request overview

Fixes the u4wrh reverse compiler emitting double-quoted header names (e.g. "X-Foo") which the hrw4u grammar's IDENT rule rejects on re-parse. Introduces a Validator.unquote_if_ident helper that strips surrounding quotes when the inner value is a valid grammar IDENT, and applies it in the set/rm and add-header reverse-emit paths.

Changes:

• Add GRAMMAR_IDENT regex (mirrors hrw4u.g4 IDENT rule) and Validator.unquote_if_ident helper.
• Use the helper in _handle_set_rm_operation and the add-header branch of _handle_statement_function in hrw_symbols.py.
• Add reverse-compiler round-trip test fixtures and a parametrized unit test, plus an exceptions entry for the asymmetric hyphen_header case.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tools/hrw4u/src/common.py	Adds GRAMMAR_IDENT regex matching the grammar IDENT rule.
tools/hrw4u/src/validation.py	Adds Validator.unquote_if_ident helper.
tools/hrw4u/src/hrw_symbols.py	Strips quotes from IDENT-safe qualifiers in set/rm and add-header reverse emit.
tools/hrw4u/tests/test_errors.py	Parametrized unit test for unquote_if_ident.
tools/hrw4u/tests/data/vars/hyphen_header.input.txt	New round-trip fixture (hrw4u source).
tools/hrw4u/tests/data/vars/hyphen_header.output.txt	Expected HRW config output.
tools/hrw4u/tests/data/vars/exceptions.txt	Marks fixture as u4wrh-direction-only.