feat: GPS-Track auf OpenSeaMap-Karte mit Leaflet visualisieren.

Leaflet wieder eingebunden, CSS über Vite gebündelt und doppelte Karten-Initialisierung behoben.

Co-authored-by: Cursor <cursoragent@cursor.com>

client/package-lock.json

@@ -15,6 +15,7 @@
         "i18next": "^26.3.0",
         "i18next-browser-languagedetector": "^8.2.1",
         "jspdf": "^4.2.1",
+        "leaflet": "^1.9.4",
         "lucide-react": "^1.16.0",
         "react": "^19.2.6",
         "react-dom": "^19.2.6",
@@ -22,6 +23,7 @@
       },
       "devDependencies": {
         "@eslint/js": "^10.0.1",
+        "@types/leaflet": "^1.9.21",
         "@types/node": "^24.12.3",
         "@types/react": "^19.2.14",
         "@types/react-dom": "^19.2.3",
@@ -2715,6 +2717,13 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/geojson": {
+      "version": "7946.0.16",
+      "resolved": "https://registry.npmjs.org/@types/geojson/-/geojson-7946.0.16.tgz",
+      "integrity": "sha512-6C8nqWur3j98U6+lXDfTUWIfgvZU+EumvpHKcYjujKH7woYyLj2sUmff0tRhrqM7BohUw7Pz3ZB1jj2gW9Fvmg==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/@types/json-schema": {
       "version": "7.0.15",
       "resolved": "https://registry.npmjs.org/@types/json-schema/-/json-schema-7.0.15.tgz",
@@ -2722,6 +2731,16 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/leaflet": {
+      "version": "1.9.21",
+      "resolved": "https://registry.npmjs.org/@types/leaflet/-/leaflet-1.9.21.tgz",
+      "integrity": "sha512-TbAd9DaPGSnzp6QvtYngntMZgcRk+igFELwR2N99XZn7RXUdKgsXMR+28bUO0rPsWp8MIu/f47luLIQuSLYv/w==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/geojson": "*"
+      }
+    },
     "node_modules/@types/node": {
       "version": "24.12.4",
       "resolved": "https://registry.npmjs.org/@types/node/-/node-24.12.4.tgz",
@@ -5299,6 +5318,12 @@
         "json-buffer": "3.0.1"
       }
     },
+    "node_modules/leaflet": {
+      "version": "1.9.4",
+      "resolved": "https://registry.npmjs.org/leaflet/-/leaflet-1.9.4.tgz",
+      "integrity": "sha512-nxS1ynzJOmOlHp+iL3FyWqK89GtNL8U8rvlMOsQdTTssxZwCXh8N2NB3GDQOL+YR3XnWyZAxwQixURb+FA74PA==",
+      "license": "BSD-2-Clause"
+    },
     "node_modules/leven": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/leven/-/leven-3.1.0.tgz",