chore: update css rules, add hct plugin

web/scripts/token-audit/parity.mjs

@@ -0,0 +1,27 @@
+// Theme parity: every color token in `:root` must also exist in
+// `[data-theme="dark"]` and vice versa. A color defined in only one theme
+// silently breaks dark mode. Derived tokens (values containing var()) adapt
+// to the theme automatically and are exempt.
+
+import { isColorValue, isDerived } from "./helpers.mjs";
+
+export function checkParity({ light, dark }) {
+	const errors = [];
+
+	// Every colorful light token must have a dark-mate (derived excluded).
+	for (const [token, value] of light) {
+		if (!isColorValue(value) || isDerived(value)) continue;
+		if (!dark.has(token)) {
+			errors.push(`  ${token} in :root has no [data-theme="dark"] override`);
+		}
+	}
+
+	// Every dark token must exist in :root (a dark-only token is orphaned).
+	for (const [token] of dark) {
+		if (!light.has(token)) {
+			errors.push(`  ${token} in [data-theme="dark"] is missing in :root`);
+		}
+	}
+
+	return errors;
+}