(refactor) extract version check workflows into reusable components

- Create check_package_version.yml reusable workflow
  - Add workspacePath input for flexible package.json location
  - Fix path concatenation to handle root directory cleanly
  - Expose version_changed and version outputs

- Create check_image_version.yml reusable workflow
  - Add workspacePath, imageName, registryUrl, registryUsername, and registryNamespace inputs
  - Make fully generic and portable across different registries
  - Fix path handling for clean path generation
  - Rename secret to registryToken for clarity

- Update build.yml to use reusable workflows
  - Replace inline jobs with workflow_call references
  - Pass all required parameters explicitly
  - Maintain existing conditional logic in build job

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.gitea/workflows/check_image_version.yml

@@ -0,0 +1,91 @@
+name: Check Image Version
+
+on:
+  workflow_call:
+    inputs:
+      workspacePath:
+        description: 'Path relative to repo root where package.json is located'
+        required: false
+        type: string
+        default: '.'
+      imageName:
+        description: 'Docker image name without registry FQDN or username'
+        required: true
+        type: string
+      registryUrl:
+        description: 'Docker registry URL (e.g., registry.budakova.org)'
+        required: false
+        type: string
+        default: 'registry.budakova.org'
+      registryUsername:
+        description: 'Docker registry username'
+        required: true
+        type: string
+      registryNamespace:
+        description: 'Docker registry namespace/organization (e.g., knee-cola)'
+        required: true
+        type: string
+    secrets:
+      registryToken:
+        description: 'Registry access token'
+        required: true
+    outputs:
+      image_exists:
+        description: 'Whether the image exists in the registry'
+        value: ${{ jobs.check_image.outputs.image_exists }}
+      version:
+        description: 'Current version from package.json'
+        value: ${{ jobs.check_image.outputs.version }}
+
+jobs:
+  check_image:
+    runs-on: ubuntu-latest
+    outputs:
+      image_exists: ${{ steps.manifest-check.outputs.image_exists }}
+      version: ${{ steps.version-read.outputs.version }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Read version from package.json
+        id: version-read
+        run: |
+          WORKSPACE_PATH="${{ inputs.workspacePath }}"
+          # Clean up path - remove trailing slash if present
+          WORKSPACE_PATH="${WORKSPACE_PATH%/}"
+          # Handle root directory case
+          if [ "$WORKSPACE_PATH" = "." ]; then
+            PACKAGE_JSON_PATH="package.json"
+          else
+            PACKAGE_JSON_PATH="${WORKSPACE_PATH}/package.json"
+          fi
+
+          VERSION=$(node -p "require('./${PACKAGE_JSON_PATH}').version")
+          echo "version=$VERSION" >> $GITHUB_OUTPUT
+          echo "Checking for image version: $VERSION"
+
+      - name: Login to Registry
+        run: |
+          echo "${{ secrets.registryToken }}" | docker login ${{ inputs.registryUrl }} -u "${{ inputs.registryUsername }}" --password-stdin
+
+      - name: Check if image exists in registry
+        id: manifest-check
+        run: |
+          VERSION=${{ steps.version-read.outputs.version }}
+          IMAGE="${{ inputs.registryUrl }}/${{ inputs.registryNamespace }}/${{ inputs.imageName }}:${VERSION}"
+
+          echo "Checking manifest for image: $IMAGE"
+
+          if docker manifest inspect "$IMAGE" &>/dev/null; then
+            echo "Image exists in registry"
+            echo "image_exists=true" >> $GITHUB_OUTPUT
+          else
+            echo "Image does not exist in registry"
+            echo "image_exists=false" >> $GITHUB_OUTPUT
+          fi
+
+      - name: Summary
+        run: |
+          echo "Version: ${{ steps.version-read.outputs.version }}"
+          echo "Image exists: ${{ steps.manifest-check.outputs.image_exists }}"