Terminplaner: Zeit (Berlin, Umstellung) und Feiertage

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

package-lock.json

@@ -13,6 +13,7 @@
         "cookie-parser": "^1.4.7",
         "dotenv": "^16.4.7",
         "express": "^4.21.2",
+        "feiertagejs": "1.5.1",
         "jose": "^6.0.11",
         "node-appwrite": "^14.1.0",
         "nodemailer": "^9.0.3",
@@ -875,6 +876,15 @@
         "url": "https://opencollective.com/express"
       }
     },
+    "node_modules/feiertagejs": {
+      "version": "1.5.1",
+      "resolved": "https://registry.npmjs.org/feiertagejs/-/feiertagejs-1.5.1.tgz",
+      "integrity": "sha512-K+erJKNcWGMmy2j9Ayn0MeinEt6LUXyQlUCjIkVR22jlPHJcI42227O+KF5/AB8MURuTUqO/kQSJwYoK/JaQHw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=8.0.0"
+      }
+    },
     "node_modules/finalhandler": {
       "version": "1.3.2",
       "resolved": "https://registry.npmjs.org/finalhandler/-/finalhandler-1.3.2.tgz",