Migrate from Next.js to SvelteKit

- Replace Next.js app with SvelteKit + adapter-node
- basePath /bodenfeuchte configured in svelte.config.js
- MQTT listener starts via hooks.server.ts on server boot
- Chart.js replaces Recharts for the moisture graph
- Dockerfile simplified: single build step, node build output
- Removed custom server.ts (no longer needed)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

deploy.sh

@@ -0,0 +1,55 @@
+#!/bin/bash
+
+set -e
+
+REGISTRY="docker.citysensor.de"
+IMAGE_NAME="bodenfeuchte"
+TAG="${1:-latest}"
+FULL_IMAGE="${REGISTRY}/${IMAGE_NAME}:${TAG}"
+BUILD_DATE=$(date +%d.%m.%Y)
+
+echo "=========================================="
+echo "Bodenfeuchte Deploy Script"
+echo "=========================================="
+echo "Registry: ${REGISTRY}"
+echo "Image: ${IMAGE_NAME}"
+echo "Tag: ${TAG}"
+echo "Build-Datum: ${BUILD_DATE}"
+echo "=========================================="
+echo ""
+
+echo ">>> Login zu ${REGISTRY}..."
+docker login "${REGISTRY}"
+echo ""
+
+echo ">>> Richte Multiplatform Builder ein..."
+if ! docker buildx inspect multiplatform-builder &>/dev/null; then
+  docker buildx create --name multiplatform-builder --driver docker-container --bootstrap
+fi
+docker buildx use multiplatform-builder
+echo ""
+
+echo ">>> Baue Multiplatform Docker Image und pushe..."
+docker buildx build \
+  --platform linux/amd64,linux/arm64 \
+  --build-arg BUILD_DATE="${BUILD_DATE}" \
+  --provenance=false \
+  -t "${FULL_IMAGE}" \
+  --push \
+  .
+
+  echo ">>> Tagge ${IMAGE_NAME} als :latest..."
+  docker buildx imagetools create \
+    -t "${REGISTRY}/${IMAGE_NAME}:latest" \
+    "${FULL_IMAGE}"
+    
+
+echo ""
+echo "=========================================="
+echo "Deploy erfolgreich abgeschlossen!"
+echo "=========================================="
+echo ""
+echo "Auf dem Server ausführen:"
+echo "  docker pull ${FULL_IMAGE}"
+echo "  docker-compose -f docker-compose.prod.yml up -d"
+echo ""