chore(ci): add pull_request trigger to image build workflow

New workflow files don't trigger push events until they exist on the
default branch. Add pull_request trigger with paths filter so images
get built during this PR.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: viniciusferrao

.github/workflows/build-ci-image.yml

@@ -2,7 +2,12 @@ name: build-ci-image
 
 on:
   push:
-    branches: [master, main, feat/ci-ubi10-container]  # TODO: remove feature branch after merge
+    branches: [master, main]
+    paths:
+      - '.devcontainer/Containerfile'
+      - '.devcontainer/Containerfile.intel'
+      - '.github/workflows/build-ci-image.yml'
+  pull_request:
     paths:
       - '.devcontainer/Containerfile'
       - '.devcontainer/Containerfile.intel'