docs(readme): improve directory structure presentation

docs(readme): clarify quick start value

docs(readme): add end-to-end example

docs(readme): add ai-safety-validation section

fix(readme): remove duplicate Playwright API validation line

docs(readme): add detailed architecture diagram

docs(readme): add problem-solution section

docs(readme): add hero section and why-testforge

refactor: complete project rename from NanoClow to TestForge

docs: update product name from NanoClow to TestForge in README

refactor: rename project from NanoClaw to TestForge

fix(agent): correct typo and improve robustness in manifest_manager

fix(agent): address code review issues in manifest_manager.py

fix: resolve code quality issues from review

fix: resolve race condition, statistics drift, import style, and duplicate config