feat(frontend): Dashboard-Ansicht (Modul 13)

/dashboard als Startseite nach Login mit Kennzahlen-Kacheln und
Hinweisen (überfällige Aufgaben, auffällige Völker, Lagerartikel
unter Mindestbestand).

ApiCore-Frontend/src/app/(app)/dashboard/page.tsx

@@ -0,0 +1,90 @@
+"use client";
+
+import Link from "next/link";
+import { useQuery } from "@tanstack/react-query";
+import { fetchDashboardAlerts, fetchDashboardSummary } from "@/lib/dashboard/api";
+import { DashboardAlert } from "@/lib/dashboard/types";
+import { Badge } from "@/components/ui/badge";
+import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
+
+function alertHref(alert: DashboardAlert): string | null {
+  if (alert.relatedType === "Colony") return `/colonies/${alert.relatedId}`;
+  if (alert.relatedType === "Task") return "/tasks";
+  if (alert.relatedType === "StockItem") return "/storage";
+  return null;
+}
+
+export default function DashboardPage() {
+  const { data: summary, isLoading: summaryLoading } = useQuery({
+    queryKey: ["dashboard", "summary"],
+    queryFn: fetchDashboardSummary,
+  });
+  const { data: alerts, isLoading: alertsLoading } = useQuery({
+    queryKey: ["dashboard", "alerts"],
+    queryFn: fetchDashboardAlerts,
+  });
+
+  const tiles = summary
+    ? [
+        { label: "Aktive Bienenstände", value: summary.apiariesActive },
+        { label: "Aktive Völker", value: summary.coloniesActive },
+        { label: "Aktive Königinnen", value: summary.queensActive },
+        { label: "Offene Aufgaben", value: summary.openTasks },
+        { label: "Honigchargen", value: summary.honeyBatchesTotal },
+        { label: "Artikel unter Mindestbestand", value: summary.stockItemsLowCount },
+      ]
+    : [];
+
+  return (
+    <main className="flex flex-col gap-6 p-4 sm:p-6">
+      <h1 className="text-xl font-semibold">Dashboard</h1>
+
+      {summaryLoading ? <p className="text-sm text-muted-foreground">Lädt…</p> : null}
+      <div className="grid grid-cols-2 gap-3 sm:grid-cols-3">
+        {tiles.map((tile) => (
+          <Card key={tile.label}>
+            <CardHeader className="pb-1">
+              <CardTitle className="text-sm font-normal text-muted-foreground">
+                {tile.label}
+              </CardTitle>
+            </CardHeader>
+            <CardContent>
+              <p className="text-2xl font-semibold">{tile.value}</p>
+            </CardContent>
+          </Card>
+        ))}
+      </div>
+
+      <Card>
+        <CardHeader>
+          <CardTitle>Hinweise</CardTitle>
+        </CardHeader>
+        <CardContent className="flex flex-col gap-2 text-sm">
+          {alertsLoading ? <p className="text-muted-foreground">Lädt…</p> : null}
+          {!alertsLoading && (!alerts || alerts.length === 0) ? (
+            <p className="text-muted-foreground">Keine offenen Hinweise.</p>
+          ) : null}
+          {alerts?.map((alert) => {
+            const href = alertHref(alert);
+            return (
+              <div
+                key={`${alert.type}-${alert.relatedId}`}
+                className="flex items-center justify-between rounded-md border p-3"
+              >
+                <span>{alert.message}</span>
+                <div className="flex items-center gap-2">
+                  <Badge variant="secondary">{alert.type}</Badge>
+                  {href ? (
+                    <Link className="underline" href={href}>
+                      Ansehen
+                    </Link>
+                  ) : null}
+                </div>
+              </div>
+            );
+          })}
+        </CardContent>
+      </Card>
+    </main>
+  );
+}

ApiCore-Frontend/src/app/(app)/layout.tsx

@@ -25,6 +25,9 @@ export default function AppLayout({ children }: { children: ReactNode }) {
       <header className="flex items-center justify-between border-b px-4 py-3">
         <nav className="flex items-center gap-4">
           <span className="font-semibold">ApiCore</span>
+          <Link className="text-sm text-muted-foreground hover:text-foreground" href="/dashboard">
+            Dashboard
+          </Link>
           <Link className="text-sm text-muted-foreground hover:text-foreground" href="/apiaries">
             Bienenstände
           </Link>

ApiCore-Frontend/src/app/(auth)/login/page.spec.tsx

@@ -28,7 +28,7 @@ describe("LoginPage", () => {
     await userEvent.click(screen.getByRole("button", { name: /anmelden/i }));
 
     expect(loginMock).toHaveBeenCalledWith("[email protected]", "ChangeMe123!");
-    expect(pushMock).toHaveBeenCalledWith("/settings/users");
+    expect(pushMock).toHaveBeenCalledWith("/dashboard");
   });
 
   it("shows an error message when login fails", async () => {

ApiCore-Frontend/src/app/(auth)/login/page.tsx

@@ -28,7 +28,7 @@ export default function LoginPage() {
     setIsSubmitting(true);
     try {
       await login(email, password);
-      router.push("/settings/users");
+      router.push("/dashboard");
     } catch {
       setError("Login fehlgeschlagen. Bitte E-Mail und Passwort prüfen.");
     } finally {