Self-healing works without a playwright.config.ts

Fixed a bug where enabling self-heal in a repo with no playwright.config.ts crashed the re-run step outright, instead of attempting a fix.

Self-healing no longer requires a playwright.config.ts file to be present in your repository. Previously, enabling self-heal in a minimal Playwright setup — no config file, just tests — caused the healed re-run to crash with a module-resolution error, so the auto-heal cycle silently produced no results.

This matters most for teams evaluating Donobu on a small proof-of-concept repo: self-healing now works from the first test you write, without any Playwright configuration boilerplate.