docs(readme): add tracing

feat(executor): add tracer/profiler options, validator, and code cleanup

doc(llm): add llms.txt for LLM code agents

fix: condition multiple precede (#104)

optimize(api): make condition task precede more user-friendly #103

fix(benchmark): fix concurency config

style(taskflow): remove unnecessary exported interface (#101)

fix(copool): deadlock may occur when goroutines end too quick under certain situation (#100)

fix(example): fix parallel sort example (#98)

doc(readme): update benchmark (#97)

perf(executor): remove unnecessary lock (#93)

style(visualizer): remove mock vizer (#96)

doc(readme): update readme doc (#95)

refactor(visualizer): remove go-graphviz and build tag

fix(test): fix skipped unit test (#92)