Add semantic version tag to Docker Hub pipeline

Extract VERSION from app/version.py and push it as an additional image
tag alongside the build ID and latest, so users can pin to a specific
release (e.g. recklessop/zerto-exporter:3.0.0).

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

azure-pipelines.yml

@@ -20,6 +20,15 @@ stages:
     pool:
       vmImage: ubuntu-latest
     steps:
+    - task: Bash@3
+      displayName: Read version from version.py
+      inputs:
+        targetType: inline
+        script: |
+          VERSION=$(python3 -c "import re; content=open('app/version.py').read(); print(re.search(r'VERSION\s*=\s*[\"\'](.*?)[\"\']', content).group(1))")
+          echo "##vso[task.setvariable variable=semanticVersion]$VERSION"
+          echo "Image version: $VERSION"
+
     - task: Docker@2
       displayName: Build and Push Image
       inputs:
@@ -29,4 +38,5 @@ stages:
         Dockerfile: '**/Dockerfile'
         tags: |
           $(Build.BuildId)
-          latest
+          $(semanticVersion)
+          latest