workflow_run triggers only fire for push events, not pull_request events,
causing PRs to skip integration and E2E tests entirely. Add dual triggers
to all test workflows so they run for both push (via workflow_run) and
pull_request events, while maintaining single-build architecture.
All workflows still pull pre-built images from docker-build.yml - no
redundant builds introduced. This fixes PR test coverage while preserving
the "Build Once, Test Many" optimization for push events.
Fixes: Build Once architecture (commit 928033ec)