Fix Cloud Run deploy: use --set-build-env-vars instead of --build-arg

The gcloud run deploy command doesn't support --build-arg directly.
Use --set-build-env-vars which Cloud Build passes to Docker as build args.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: cbullinger

.github/workflows/ci.yml

@@ -125,7 +125,7 @@ jobs:
             --allow-unauthenticated \
             --env-vars-file=env-cloudrun.yaml \
             --set-env-vars="GITHUB_APP_ID=${{ secrets.GITHUB_APP_ID }},INSTALLATION_ID=${{ secrets.INSTALLATION_ID }}" \
-            --build-arg="VERSION=${{ steps.version.outputs.tag }}" \
+            --set-build-env-vars="VERSION=${{ steps.version.outputs.tag }}" \
             --tag="${{ steps.version.outputs.tag }}" \
             --max-instances=10 \
             --cpu=1 \

Dockerfile

@@ -1,7 +1,9 @@
 # Build stage
 FROM golang:1.26.0-alpine AS builder
 
-# Version is set at build time (e.g. docker build --build-arg VERSION=v1.0.0)
+# Version is set at build time via:
+# - Docker: docker build --build-arg VERSION=v1.0.0
+# - Cloud Run: gcloud run deploy --set-build-env-vars VERSION=v1.0.0
 ARG VERSION=dev
 
 # Install build dependencies