fix: preserve [complete] extra in langflow-base pre-release constraint (#11931)

* fix: preserve [complete] extra in langflow-base pre-release constraint

The sed replacement for pre-release builds was dropping the [complete]
extra from the langflow-base dependency, causing the built wheel to
depend on bare langflow-base instead of langflow-base[complete]. This
meant hundreds of optional dependencies (LLM providers, vector stores,
document loaders, etc.) were missing from pre-release installs, breaking
the CLI and all cross-platform installation tests.

* test: add regression test for sed constraint preservation

* [autofix.ci] apply automated fixes

* test: add regression test for sed constraint preservation in release workflow

* [autofix.ci] apply automated fixes

* test: add regression test for sed constraint preservation in release workflow

* [autofix.ci] apply automated fixes

* fix: move noqa comment to correct line for S603 check

* [autofix.ci] apply automated fixes

* test: add regression test for sed constraint preservation in release workflow

* [autofix.ci] apply automated fixes

* test: add regression test for sed constraint preservation in release workflow

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Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>