Add optimized Gitea CI/CD workflows for Docker builds

Features:
- docker-autobuild.yaml: Automated builds on push to main/master
  - Path ignores for markdown/docs files
  - Docker Buildx with caching support
  - Automatic cleanup after builds

- docker-build.yaml: Manual builds with flexible options
  - Custom version tags
  - Additional tags support (e.g., stable,production)
  - Toggle latest tag
  - Docker Buildx with layer caching

Both workflows:
- Use registry credentials from Gitea secrets
- Support local registry at 192.168.88.201:5000
- Proper login/logout handling
- Optimized for sticker-bot project

.gitea/workflows/docker-autobuild.yaml

@@ -0,0 +1,63 @@
+name: Auto Build and Push Docker Image
+
+on:
+  push:
+    branches:
+      - main
+      - master
+    paths-ignore:
+      - '**.md'
+      - '.gitignore'
+      - 'data/**'
+      - '.env.example'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Docker Registry
+        run: |
+          echo "${{ secrets.REGISTRY_PASSWORD }}" | docker login -u "${{ secrets.REGISTRY_USERNAME }}" --password-stdin 192.168.88.201:5000 || true
+
+      - name: Build and Push Docker Image
+        run: |
+          REGISTRY="192.168.88.201:5000"
+          IMAGE_NAME="${{ gitea.repository }}"
+          
+          # Versionierung: v{run_number}-autobuild
+          VERSION="v${{ gitea.run_number }}-autobuild"
+          FULL_IMAGE_PATH="$REGISTRY/$IMAGE_NAME"
+          
+          echo "========================================"
+          echo "Building Docker Image"
+          echo "Registry: $REGISTRY"
+          echo "Image: $IMAGE_NAME"
+          echo "Version: $VERSION"
+          echo "========================================"
+          
+          # Build with cache
+          docker build \
+            --cache-from $FULL_IMAGE_PATH:latest \
+            -t $FULL_IMAGE_PATH:latest \
+            -t $FULL_IMAGE_PATH:$VERSION \
+            .
+          
+          # Push images
+          docker push $FULL_IMAGE_PATH:latest
+          docker push $FULL_IMAGE_PATH:$VERSION
+          
+          echo "✅ Successfully built and pushed:"
+          echo "  - $FULL_IMAGE_PATH:latest"
+          echo "  - $FULL_IMAGE_PATH:$VERSION"
+
+      - name: Cleanup
+        if: always()
+        run: |
+          docker logout 192.168.88.201:5000 || true
+          docker system prune -f || true

.gitea/workflows/docker-build.yaml

@@ -0,0 +1,90 @@
+name: Manual Build and Push Docker Image
+
+on:
+  workflow_dispatch:
+    inputs:
+      tag_name:
+        description: 'Version tag (e.g., 1.0.0, v1.0.0). Leave empty for auto-generated v{run_number}.'
+        required: false
+        default: ''
+      additional_tags:
+        description: 'Additional tags (comma-separated, e.g., stable,production)'
+        required: false
+        default: ''
+      push_latest:
+        description: 'Also push as latest?'
+        required: true
+        default: 'true'
+        type: boolean
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Docker Registry
+        run: |
+          echo "${{ secrets.REGISTRY_PASSWORD }}" | docker login -u "${{ secrets.REGISTRY_USERNAME }}" --password-stdin 192.168.88.201:5000 || true
+
+      - name: Build and Push Docker Image
+        run: |
+          REGISTRY="192.168.88.201:5000"
+          IMAGE_NAME="${{ gitea.repository }}"
+          FULL_IMAGE_PATH="$REGISTRY/$IMAGE_NAME"
+          
+          # Determine version
+          if [ -z "${{ github.event.inputs.tag_name }}" ]; then
+            VERSION="v${{ gitea.run_number }}"
+          else
+            VERSION="${{ github.event.inputs.tag_name }}"
+          fi
+          
+          echo "========================================"
+          echo "Building Docker Image (Manual)"
+          echo "Registry: $REGISTRY"
+          echo "Image: $IMAGE_NAME"
+          echo "Version: $VERSION"
+          echo "========================================"
+          
+          # Build with cache
+          docker build \
+            --cache-from $FULL_IMAGE_PATH:latest \
+            -t $FULL_IMAGE_PATH:$VERSION \
+            .
+          
+          # Push versioned tag
+          docker push $FULL_IMAGE_PATH:$VERSION
+          echo "✅ Pushed: $FULL_IMAGE_PATH:$VERSION"
+          
+          # Push latest if enabled
+          if [ "${{ github.event.inputs.push_latest }}" = "true" ]; then
+            docker tag $FULL_IMAGE_PATH:$VERSION $FULL_IMAGE_PATH:latest
+            docker push $FULL_IMAGE_PATH:latest
+            echo "✅ Pushed: $FULL_IMAGE_PATH:latest"
+          fi
+          
+          # Push additional tags
+          if [ -n "${{ github.event.inputs.additional_tags }}" ]; then
+            IFS=',' read -ra TAGS <<< "${{ github.event.inputs.additional_tags }}"
+            for tag in "${TAGS[@]}"; do
+              tag=$(echo $tag | xargs)  # trim whitespace
+              docker tag $FULL_IMAGE_PATH:$VERSION $FULL_IMAGE_PATH:$tag
+              docker push $FULL_IMAGE_PATH:$tag
+              echo "✅ Pushed: $FULL_IMAGE_PATH:$tag"
+            done
+          fi
+          
+          echo "========================================"
+          echo "Build completed successfully!"
+          echo "========================================"
+
+      - name: Cleanup
+        if: always()
+        run: |
+          docker logout 192.168.88.201:5000 || true
+          docker system prune -f || true