fix(ci): use stable git-SHA tag for deployment instead of timestamp

Changed IMAGE_TAG output from timestamp-based format to stable git-SHA format to ensure
deployment can reliably pull the image that was actually pushed to the registry.

Before: IMAGE_TAG="6c7040e-1762265632" (changes with time)
After: IMAGE_TAG="git-6c7040e" (stable, matches pushed tag)

This fixes deployment manifest not found errors.

.gitea/workflows/build-image.yml

@@ -884,7 +884,8 @@ jobs:
 
           REGISTRY_TO_USE="${REGISTRY_URL:-$REGISTRY_DEFAULT}"
 
-          IMAGE_TAG="$TAG"
+          # Use git-SHA format for deployment (stable, doesn't change with time)
+          IMAGE_TAG="git-${SHORT_SHA}"
           IMAGE_URL="${REGISTRY_TO_USE}/${IMAGE_NAME}:${IMAGE_TAG}"
 
           echo "IMAGE_TAG=$IMAGE_TAG" >> "$GITHUB_OUTPUT"
@@ -892,7 +893,8 @@ jobs:
           echo "COMMIT_SHA=$COMMIT_SHA" >> "$GITHUB_OUTPUT"
 
           echo "📦 Image info:"
-          echo "   Tag: $IMAGE_TAG"
+          echo "   Tag: $IMAGE_TAG (stable git-based tag)"
+          echo "   Also pushed: $TAG (timestamped), latest"
           echo "   URL: $IMAGE_URL"
           echo ""