- switch local and remote curl assertions to substring checks for dynamic HTTP responses

- add per-run build markers to restarthelper fixtures to avoid cached image reuse
- retry sync writes until the remote file reflects the change instead of assuming watcher readiness
- sanitize terminal output parsing so pod name detection is resilient to control characters
- deduplicate image tag lookup logic in build tests
- clean up env var set/unset handling across e2e tests to satisfy errcheck