Fix: /dashboard 500 – buttonCls aus Client-Modul herausgelöst

Server-Komponenten (Dashboard, Aufträge, Suche, Checklisten, Auftragsdetail) riefen
buttonCls() aus einem "use client"-Modul auf; das bricht zur Laufzeit (gemeldet von L8).
Neu: src/components/work-orders/button-cls.ts (server-sicher), action-form re-exportiert.

Nachweis: authentifizierter HTTP-Smoke (Backoffice 13 Seiten, Monteur 6 Seiten) alle 200,
/dashboard vorher 500. tsc/lint grün.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/components/work-orders/button-cls.ts

@@ -0,0 +1,21 @@
+import { cn } from "@/lib/utils";
+
+/**
+ * Button class names shared by server and client components. Kept out of "use client" modules:
+ * calling a function exported from a client module inside a server component fails at runtime.
+ */
+const VARIANTS = {
+  primary: "bg-cta text-cta-foreground hover:opacity-90",
+  default: "bg-primary text-primary-foreground hover:opacity-90",
+  outline: "border border-border bg-background hover:bg-muted",
+  danger: "border border-[var(--risk)] bg-background text-[var(--risk)] hover:bg-muted",
+  ghost: "hover:bg-muted text-muted-foreground",
+} as const;
+
+export type ButtonVariant = keyof typeof VARIANTS;
+
+export const buttonCls = (variant: ButtonVariant = "default") =>
+  cn(
+    "inline-flex min-h-11 items-center justify-center gap-2 rounded-lg px-4 font-heading text-sm font-semibold transition-colors focus-visible:ring-3 focus-visible:ring-ring/50 focus-visible:outline-none disabled:opacity-50",
+    VARIANTS[variant],
+  );