fix: add fail-fast: false to prevent cascade cancellations in matrix build

When protoc-go fails, the default fail-fast behaviour cancels all
subsequent matrix jobs (protoc-java, protoc-node, protoc-swift,
protoc-web). Setting fail-fast: false allows each image to be
independently built and pushed regardless of other image failures.

https://claude.ai/code/session_01Ec67FjhM1vVv6ZDBtpUb9F

Author: claude

.github/workflows/build-protoc.yml

@@ -15,6 +15,7 @@ jobs:
     strategy:
       # ensure protoc is built first
       max-parallel: 1
+      fail-fast: false
       matrix:
         image:
           - protoc