phase-card: replace index prop with explicit stepNumber

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/features/prozess/components/phase-card.tsx

@@ -10,7 +10,7 @@ interface PhaseCardProps {
 	label: string;
 	beschreibung: string;
 	status: PhaseStatus;
-	index: number;
+	stepNumber: number;
 	children?: ReactNode;
 }
 
@@ -18,7 +18,7 @@ export function PhaseCard({
 	label,
 	beschreibung,
 	status,
-	index,
+	stepNumber,
 	children,
 }: PhaseCardProps) {
 	const [expanded, setExpanded] = useState(false);
@@ -46,7 +46,7 @@ export function PhaseCard({
 								"border-muted-foreground/40 text-muted-foreground/40",
 						)}
 					>
-						{status === "erledigt" ? <Check className="size-4" /> : index + 1}
+						{status === "erledigt" ? <Check className="size-4" /> : stepNumber}
 					</div>
 					<div className="flex min-w-0 flex-1 flex-col gap-1">
 						<div className="flex items-center gap-2">