ci(build): publish versioned image on semver tag push

Add tag trigger (v*.*.*) and semver image tags so pushing a release
tag publishes :0.9.0 and :0.9 alongside the existing :latest from
main. Git tags stay v-prefixed; image tags drop the prefix per
Docker convention.

Author: mxhash

.github/workflows/build-image.yml

@@ -3,6 +3,7 @@ name: Build container image
 on:
   push:
     branches: [main]
+    tags: ["v*.*.*"]
   pull_request:
     branches: [main]
 
@@ -37,6 +38,8 @@ jobs:
           tags: |
             type=raw,value=latest,enable={{is_default_branch}}
             type=ref,event=pr,prefix=pr-
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
 
       - name: Build and push
         uses: docker/build-push-action@v6