fix(deployment): remove the helper container before restarting it with the same name

Docker frees the name of a stopped --rm container in the background, so
the second helper docker run for build secrets could fail with a name
conflict. Remove the old helper with docker rm -f before the run.

Closes #9363

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -20,6 +20,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ### Fixed
 
+- Fix deployments that failed with "The container name ... is already in use" when **Use build secrets** is on. To set the real `SOURCE_COMMIT`, Coolify starts the helper container a second time with the same name. Before, Coolify stopped the old helper and started the new one immediately, but Docker removes a stopped `--rm` container in the background, so the name was sometimes still in use. Coolify now removes the old helper and waits until Docker frees the name ([#9363](https://github.com/coollabsio/coolify/issues/9363))
 - Fix Docker builds that failed with "BuildKit is enabled but the buildx component is missing or broken" when the application has a build-time variable `HOME` or `DOCKER_CONFIG`. Coolify loads the build-time variables before it runs `docker build` in the helper container, so the variable moved the Docker CLI away from its plugins in `/root/.docker/cli-plugins`. The Docker CLI in the helper now always uses `/root/.docker`. A `HOME` build argument keeps its value ([#9726](https://github.com/coollabsio/coolify/issues/9726))
 - Keep the trailing newline of multiline environment variables, for example an SSH private key that a Dockerfile mounts as a build secret. Before, Coolify removed the edge whitespace of every value, so OpenSSH rejected the key with "error in libcrypto". A value with more than one line is now saved exactly as you enter it, in the UI and in the API. Single-line values still lose their edge whitespace. Save a variable again to add the newline that Coolify removed before ([#9438](https://github.com/coollabsio/coolify/issues/9438))
 - Use the same `COOLIFY_BRANCH` value in all parts of a preview deployment: `pull/<pull request number>/head`. Before, a variable that refers to `${COOLIFY_BRANCH}` got the branch of the application (for example `main`), but the container got `pull/<number>/head`. Other build packs got `pull/<number>/head:pr-<number>-coolify`, and applications from a public repository got the branch of the application ([#9572](https://github.com/coollabsio/coolify/issues/9572))