feat: enhance ChangeAPI and ChangePreferences components; add "API key update" functionality and save preferences feature

frontend/src/components/Header.tsx

@@ -75,6 +75,31 @@ const Header: React.FC = () => {
               Preferences
             </span>
           </button>
+          <a
+            href="https://git.the1s.de/theis.gaedigk/weather-app/wiki"
+            target="_blank"
+            rel="noopener noreferrer"
+          >
+            <button className="bg-white text-blue-700 font-bold px-6 py-3 rounded-xl shadow-lg hover:bg-blue-100 transition-all border border-blue-200 flex items-center gap-2">
+              <span className="flex items-center gap-2">
+                <svg
+                  xmlns="http://www.w3.org/2000/svg"
+                  fill="none"
+                  viewBox="0 0 24 24"
+                  strokeWidth={1.5}
+                  stroke="currentColor"
+                  className="size-6"
+                >
+                  <path
+                    strokeLinecap="round"
+                    strokeLinejoin="round"
+                    d="M19.5 14.25v-2.625a3.375 3.375 0 0 0-3.375-3.375h-1.5A1.125 1.125 0 0 1 13.5 7.125v-1.5a3.375 3.375 0 0 0-3.375-3.375H8.25m5.231 13.481L15 17.25m-4.5-15H5.625c-.621 0-1.125.504-1.125 1.125v16.5c0 .621.504 1.125 1.125 1.125h12.75c.621 0 1.125-.504 1.125-1.125V11.25a9 9 0 0 0-9-9Zm3.75 11.625a2.625 2.625 0 1 1-5.25 0 2.625 2.625 0 0 1 5.25 0Z"
+                  />
+                </svg>
+                Docs
+              </span>
+            </button>
+          </a>
         </div>
       </header>
       {apiCard && (
@@ -87,7 +112,10 @@ const Header: React.FC = () => {
             >
               &times;
             </button>
-            <ChangeAPI currentAPIKey={apiKey} />
+            <ChangeAPI
+              currentAPIKey={apiKey}
+              onClose={() => setApiCard(false)}
+            />
           </div>
         </div>
       )}
@@ -102,7 +130,7 @@ const Header: React.FC = () => {
             >
               &times;
             </button>
-            <ChangePreferences />
+            <ChangePreferences onClose={() => setPreferencesCard(false)} />
           </div>
         </div>
       )}