Replace lib/version.ts with APP_VERSION build arg injected via Docker

Remove the static package.json import in lib/version.ts and instead
pass APP_VERSION as a Docker build arg extracted from package.json by
the CI workflow. Both the builder and runner stages receive APP_VERSION
and GIT_COMMIT_SHA as environment variables, making runtime version
info available via process.env without bundling package.json into the
standalone output.

.github/workflows/docker.yml

@@ -39,6 +39,10 @@ jobs:
           username: ${{ vars.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
+      - name: Get app version
+        id: version
+        run: echo "version=$(jq -r .version package.json)" >> "$GITHUB_OUTPUT"
+
       - name: Docker metadata
         id: meta
         uses: docker/metadata-action@v5
@@ -62,6 +66,7 @@ jobs:
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
           build-args: |
+            APP_VERSION=${{ steps.version.outputs.version }}
             GIT_COMMIT_SHA=${{ github.sha }}
           cache-from: type=gha
           cache-to: type=gha,mode=max