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/admin/catalog-manager/catalog-manager-dialog.tsx

@@ -74,7 +74,7 @@ export function CatalogManagerDialog({
 			{mounted && open
 				? createPortal(
 						<div className="fixed inset-0 z-[200]">
-							<div className="absolute inset-0 bg-black/70" />
+							<div className="absolute inset-0 bg-foreground/70" />
 							<div
 								role="dialog"
 								aria-modal="true"