ci: disable auto-trigger on build.yml (no PyPI publishing for fork)

opensensor/fief is a deployment fork - we don't publish to PyPI.
Changed trigger from push/pull_request to workflow_dispatch only so
the lint/test/pypi pipeline no longer fails on every commit.
Use docker-image.yml for automated Docker image publishing.

Author: matteius

.github/workflows/build.yml

@@ -1,8 +1,10 @@
 name: Build
 
+# This workflow is kept for reference but disabled from automatic triggers.
+# opensensor/fief does not publish to PyPI; use docker-image.yml for releases.
+# Trigger manually via GitHub UI -> Actions -> Build -> Run workflow if needed.
 on:
-  push:
-  pull_request:
+  workflow_dispatch:
 
 jobs:
   lint: