fix(ci): build Docker Hub images from repository Dockerfile

[N2H4-xz]

Summary

• point the two flowiseai/flowise Docker Hub matrix entries at the repository-root ./Dockerfile;
• keep the worker images on docker/worker/Dockerfile;
• add a regression assertion to the Docker smoke workflow so the release matrix cannot silently select the wrong Dockerfile again.

Root cause

The Docker Hub release workflow used ./docker/Dockerfile for the main Flowise image. That Dockerfile performs an unlocked global package installation, which allowed incompatible package versions into the published image. The repository-root Dockerfile builds from the checked-in source and lockfile.

Validation

• the new matrix assertion passes on this branch;
• the same assertion fails against the unmodified HEAD, which still maps the main image to ./docker/Dockerfile;
• both changed workflow files parse as YAML;
• actionlint passes for the changed workflows after filtering pre-existing ShellCheck diagnostics in the repository;
• git diff --check passes;
• the existing source-build image smoke evidence returns pong from /api/v1/ping.

Fixes #6688.

Collaboration and AI assistance

This fix was developed collaboratively by the human contributor, MiMo Code, and GPT assistance. The human contributor reviewed and approved the implementation, tests, and draft PR; maintainer review is still requested.

[gemini-code-assist]

Caution

The consumer version of Gemini Code Assist on GitHub has been sunset. All code review activity has officially ceased.

[gemini-code-assist]

Caution

The consumer version of Gemini Code Assist on GitHub has been sunset. All code review activity has officially ceased.