Add detectClaudeLoginRequired and extractClaudeLoginUrl to parse module.
Extract buildClaudeRuntimeConfig for reuse by both execute and the new
runClaudeLogin helper. Include errorCode: "claude_auth_required" and
errorMeta: { loginUrl } in execution results when login is needed.
Export runClaudeLogin from the package index.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>