Markdown $…$/$$…$$ and org $…$, \(…\), \[…\] render server-side as MathML through internal/texmath, a converter for a documented TeX subset (no dependency; the one pure-Go candidate put input into attributes unescaped and expanded macros without bound). Invalid or unsupported TeX shows as escaped source. Converter output is sanitized with its own policy and placed after the document is sanitized; raw user MathML is still stripped. Linear scanning, a per-document budget of 1000 expressions or 256 KiB, and a fuzz target. CSP unchanged. Parity/Users/CHANGELOG.
Closes #294