chore: Add .playwright-mcp to .gitignore

- Exclude Playwright MCP screenshot cache from version control

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.gitignore

@@ -41,3 +41,4 @@ next-env.d.ts
 /test-results/
 /playwright-report/
 /playwright/.cache/
+.playwright-mcp/