[dajiaohuang]

Problem

Fixes #412.

With --vertical-align, a supported CHECK (description <> '') expression prevents alignment of that table and subsequent tables. The tokenizer's single-quoted-string alternative requires at least one character, so the fallback token consumes '' together with following closing parentheses. The alignment pass then loses track of the table body's depth.

Change

Allow an empty single-quoted token using the existing string-token rule. Add a public Beautify API regression for the affected table and an independent following table, also checking preservation of the literal.

Validation

• New regression: fails 2 of 3 assertions at master 57cd377321c8474a17ae59a139efa9c4019f21bd, passes all 3 with this change (Ubuntu 24.04, Perl 5.38.2).
• Synthetic CLI CHECK example now aligns both tables and remains idempotent.
• Bounded synthetic CLI checks for stdin/files/output/inplace, config precedence/discovery, case/indent/comments/functions and selected options; public Perl API and DESTDIR installation/installed CLI smoke test passed.
• git diff --check passed.

Only synthetic SQL was formatted; no SQL was executed. Full upstream SQL regression corpus and Perl-version CI matrix were not run locally. CGI runtime was not tested because CGI.pm is absent in the local Perl environment.