refactor(theming): replace red-* palette with semantic error-* tokens

Sweep 30 files: text/bg/border/ring/from/to/via/fill/stroke/shadow/divide/decoration/
outline/placeholder-red-N → -error-N. All red usages were semantically error/danger
(no brand red), so tokens now flow through the design-system CSS variables and respond
to palette overrides.

src/pages/AdminPolicyEdit.tsx

@@ -455,7 +455,7 @@ export default function AdminPolicyEdit() {
                   onClick={() => setFormData((prev) => ({ ...prev, effect: 'deny' }))}
                   className={`flex-1 rounded-lg border px-3 py-2 text-sm font-medium transition-colors ${
                     formData.effect === 'deny'
-                      ? 'border-red-500/50 bg-red-500/10 text-red-400'
+                      ? 'border-error-500/50 bg-error-500/10 text-error-400'
                       : 'border-dark-600 bg-dark-900 text-dark-400 hover:border-dark-500'
                   }`}
                 >