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/app/(site)/register/page.tsx

@@ -100,7 +100,7 @@ export default async function RegisterPage() {
 													"var(--color-primary-readable, var(--color-primary))",
 											}}
 										>
-											<span className="w-2 h-2 rounded-full bg-green-500" />
+											<span className="w-2 h-2 rounded-full bg-primary" />
 											{tpr("usersOnline", { count: online })}
 										</div>
 										<h1