fix: Cherry-pick nightly SDK build fixes to main (#12491)

* fix: Build and install the langflow-sdk for lfx (fixes nightly) (#12481)

* fix: Build and install the langflow-sdk for lfx

* Publish sdk as a nightly

* Update ci.yml

* Update python_test.yml

* Update ci.yml

* fix: Properly grep for the langflow version (#12486)

* fix: Properly grep for the langflow version

* Mount the sdk where needed

* Skip the sdk

* [autofix.ci] apply automated fixes

* Update setup.py

* fix(docker): Remove broken npm self-upgrade from Docker images (#12309)

* fix: replace grep -oP with sed for Node.js version extraction in Docker builds (#12331)

The grep -oP (PCRE regex) command fails in the python:3.12.12-slim-trixie
Docker base image because PCRE support is not available in the slim variant.

This replaces grep -oP with portable sed -nE in all 5 Dockerfiles and adds
an empty version guard to fail fast with a clear error message instead of
producing a broken download URL.

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Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Cristhian Zanforlin Lousa <cristhian.lousa@gmail.com>
Co-authored-by: vjgit96 <vijay.katuri@ibm.com>