/**
* HTML Attribute Security Pass
*
* Runs attribute-level security checks directly on the HTML AST.
* These rules do not require IR — they operate on element attributes.
*
* Rules:
* H1: html-missing-noopener (CWE-1022) — without rel="noopener"
* H2: html-javascript-uri (CWE-79) — javascript: in href/src/action
* H3: html-missing-sandbox (CWE-1021) —