Replace the regex/escape-normalizer with @csstools/css-tokenizer (already
present transitively). Tokenizing resolves comments, hex escapes, and line
continuations into the real value before scanning, so obfuscated forms (a
scheme split by a line continuation or hex escape) cannot slip past. Scan
url-tokens and string-tokens to cover url(), quoted @import, and string-form
image functions. Add regression tests for the bypasses.