feat: enforce no hardcoded colors across entire CMS

Added scripts/check-admin-colors.mjs — scans all src/ files for:
- text-white, text-black (use theme text vars)
- bg-white, bg-black (use theme background/overlay vars)
- bg/text/border/ring with gray/slate/zinc/stone palette
- bg/text/border/ring with red/green/blue/etc palette

Fixed 21 violations across 11 files:
- Overlays: bg-black/* → bg-foreground/*
- Text: text-white → text-primary-foreground
- Backgrounds: bg-white/10 → bg-background/10
- Green accents: bg-green-* → bg-primary
- Red accents: bg-red-* → bg-destructive

Integrated into:
- lint-staged: runs on every *.ts/*.tsx commit
- vitest: src/lib/no-hardcoded-colors.test.ts replaces old audit test
- Allowlist: shadcn/ui primitives (button, badge, dialog) + 4 graphical files

src/components/top-header.tsx

@@ -231,7 +231,7 @@ export async function TopHeader({ session }: { session: Session | null }) {
 					</form>
 					<Link
 						href="/messages"
-						className="relative flex items-center gap-1 rounded-lg px-1.5 sm:px-2 py-1.5 transition-colors hover:bg-white/10"
+						className="relative flex items-center gap-1 rounded-lg px-1.5 sm:px-2 py-1.5 transition-colors hover:bg-background/10"
 					>
 						<svg
 							xmlns="http://www.w3.org/2000/svg"
@@ -376,7 +376,7 @@ export async function TopHeader({ session }: { session: Session | null }) {
 											<Link
 												key={u.id}
 												href="/messages"
-												className="flex items-center gap-2 rounded-lg px-2 py-1 text-xs transition-colors hover:bg-white/10"
+												className="flex items-center gap-2 rounded-lg px-2 py-1 text-xs transition-colors hover:bg-background/10"
 											>
 												<UserAvatarThumbnail
 													figure={u.look}