SQL minifier

Collapses a SQL statement onto one line and strips comments, without touching what is inside a string literal — which is where every naive whitespace-squasher goes wrong.

The whole difficulty is string literals. A regex that replaces runs of whitespace with a single space will happily rewrite `WHERE note = 'a b'` into `'a b'`, silently changing what the query matches. The minifier here tracks quoting, so text inside a literal survives exactly, doubled apostrophes included. Comments are removed on the same terms: `--` to end of line and `/* … */`, but only where they are not inside a string. A URL in a literal contains `--` surprisingly often, and a comment stripper that does not know it is inside a quote will truncate the value. Worth saying plainly: minifying SQL saves almost nothing. Query text is a rounding error next to the work the database does, and a minified query is far harder to debug in a slow-query log. The genuine uses are fitting a statement into a single-line config value, a migration tool that wants one statement per line, or a log line that must not wrap.