fix(security): sanitize badge_wall_css server-side, render via textContent

Custom badge-wall CSS was sanitised only client-side with a fragile regex
and injected via innerHTML, while the stored value stayed raw. Sanitise
at the write boundary instead (setCSS, covering both the REST and GraphQL
paths) with a css-tree pass that parses leniently and drops @import,
behavior/-moz-binding, expression()/javascript: values, and </style>
break-out attempts; render with textContent instead of innerHTML so
break-out is impossible by construction (CSP already blocks inline
script). css-tree stays server-only. A behaviour-gate test confirms
ordinary CSS (backdrop-filter, content, url(), @media, @keyframes) is
preserved while the dangerous constructs are removed.

The previous regex also silently stripped all `content:` declarations;
those now render correctly.

0 files changed, 0 insertions, 0 deletions