feat: add Navigation component and update layout for Items and Tags pages

frontend/src/App.tsx

@@ -1,5 +1,5 @@
 import React, { useState, useEffect } from "react";
-import { BrowserRouter as Router, Routes, Route, Link, Navigate, useNavigate } from "react-router-dom";
+import { BrowserRouter as Router, Routes, Route, Link, useLocation, Navigate, useNavigate } from "react-router-dom";
 import { getSeed, getTrips, getNextTripId } from "./api";
 import ItemsPage from "./pages/ItemsPage";
 import TripChecklist from "./pages/TripChecklist";
@@ -21,6 +21,74 @@ function NextTripRedirect({ trips }: { trips: any[] }) {
   return <Navigate to={`/trips/${nextTripId}`} replace />;
 }
 
+function Navigation() {
+  const location = useLocation();
+  const navItems = [
+    { to: "/trips", label: "Trips" },
+    { to: "/items", label: "Items" },
+    { to: "/tags", label: "Tags" },
+  ];
+
+  // Navigation für den Titel-Link
+  const navigate = useNavigate();
+  async function goToCurrentTrip() {
+    try {
+      const id = await getNextTripId();
+      navigate(`/trips/${id}`);
+    } catch {
+      alert("Kein anstehender Trip gefunden");
+    }
+  }
+
+  // Prüfe, ob ein einzelner Trip angezeigt wird
+  const isTripDetail = /^\/trips\/[^/]+$/.test(location.pathname);
+
+  return (
+    <nav className="mb-8 flex items-center gap-4 bg-white/80 backdrop-blur border-b border-gray-200 px-2 py-2 rounded-xl shadow-sm">
+      <button
+        className="text-2xl font-extrabold text-blue-700 tracking-tight mr-4 select-none hover:underline bg-transparent p-0"
+        style={{ background: "none", border: "none" }}
+        onClick={goToCurrentTrip}
+        title="Zum aktuellen Trip"
+      >
+        Packliste
+      </button>
+      {navItems.map((item) => {
+        // Trips ist NICHT aktiv, wenn ein einzelner Trip angezeigt wird
+        const isActive =
+          !isTripDetail && location.pathname.startsWith(item.to);
+        return (
+          <Link
+            key={item.to}
+            to={item.to}
+            className={
+              "px-4 py-2 rounded font-medium transition " +
+              (isActive
+                ? "bg-blue-600 text-white shadow"
+                : "text-blue-700 hover:bg-blue-100 hover:text-blue-900")
+            }
+            style={{
+              boxShadow: isActive ? "0 2px 8px 0 rgba(37,99,235,0.08)" : undefined,
+              border: isActive ? "2px solid #2563eb" : undefined,
+            }}
+          >
+            {item.label}
+          </Link>
+        );
+      })}
+      <button
+        className="ml-auto bg-gray-100 text-gray-700 px-4 py-2 rounded hover:bg-gray-200 transition"
+        onClick={async () => {
+          await getSeed();
+          window.location.reload();
+        }}
+      >
+        Seed-Daten erzeugen
+      </button>
+    </nav>
+  );
+}
+
 export default function App() {
   const [trips, setTrips] = useState<any[]>([]);
   const navigate = useNavigate();
@@ -45,41 +113,7 @@ export default function App() {
 
   return (
     <div className="p-4 max-w-5xl mx-auto">
-      <h1 className="text-2xl font-bold mb-4">Packlist</h1>
-
-      <div className="flex gap-2 mb-4">
-        <button
-          className="bg-yellow-500 text-white px-4 py-2 rounded"
-          onClick={goToCurrentTrip}
-        >
-          Zum aktuellen Trip
-        </button>
-        <Link to="/trips">
-          <button className="bg-blue-500 text-white px-4 py-2 rounded">
-            Trips
-          </button>
-        </Link>
-        <Link to="/items">
-          <button className="bg-green-500 text-white px-4 py-2 rounded">
-            Items
-          </button>
-        </Link>
-        <Link to="/tags">
-          <button className="bg-purple-500 text-white px-4 py-2 rounded">
-            Tags
-          </button>
-        </Link>
-        <button
-          className="bg-gray-300 text-gray-800 px-4 py-2 rounded"
-          onClick={async () => {
-            await getSeed();
-            await loadTrips();
-          }}
-        >
-          Seed-Daten erzeugen
-        </button>
-      </div>
-
+      <Navigation />
       <Routes>
         <Route path="/trips" element={<TripsPage />} />
         <Route path="/trips/:id" element={<TripChecklist trips={trips} />} />

frontend/src/pages/ItemsPage.tsx

@@ -127,7 +127,7 @@ export default function ItemsPage() {
   }
 
   return (
-    <div className="p-4 max-w-3xl mx-auto">
+    <div className="p-2">
       <h1 className="text-2xl font-bold mb-4">Items</h1>
 
       <div className="mb-4 flex items-center gap-2">

frontend/src/pages/TagsPage.tsx

@@ -49,7 +49,7 @@ export default function TagsPage() {
   }
 
   return (
-    <div className="p-4 max-w-xl mx-auto">
+    <div className="p-2">
       <h1 className="text-2xl font-bold mb-4">Alle Tags</h1>
       <form className="flex gap-2 mb-6" onSubmit={handleCreate}>
         <input

frontend/src/pages/TripsPage.tsx

@@ -72,8 +72,8 @@ export default function TripsPage() {
   }
 
   return (
-    <div>
-      <h1 className="text-2xl font-bold mb-4">Packlist</h1>
+    <div className="p-2">
+      <h1 className="text-2xl font-bold mb-4">Trips</h1>
       <button
         className="mb-4 bg-blue-500 text-white px-4 py-2 rounded"
         onClick={() => setShowForm((v) => !v)}