feat(workflow): add conditional branch (If-Else) node * feature/20251219_myh: (10 commits) fix(workflow): fix run_workflow streaming issues fix(prompt-optimizer): switch to built-in system prompt feat(workflow): add conditional branch (If-Else) node perf(types): add Union type declaration for workflow nodes fix(expression-eval): fix variable extraction issue in Jinja2 templates docs(samples): add config example for If-Else node style(workflow): update condition edge comments for conditional nodes style(enums): correct enum class name spelling refactor(workflow): unify all enum classes in one file and restructure workflow... feat(workflow): add import for if-else node configuration Signed-off-by: Eternity <1533512157@qq.com> Commented-by: Eternity <1533512157@qq.com> Reviewed-by: zhuwenhui5566@163.com <zhuwenhui5566@163.com> Merged-by: zhuwenhui5566@163.com <zhuwenhui5566@163.com> CR-link: https://codeup.aliyun.com/redbearai/python/redbear-mem-open/change/17