fix: include pro/squads in npm tarball for pro scaffold (#562)

* fix: include pro/squads in npm tarball for pro scaffold

The package.json files field only included pro/license/, causing
stepInstallScaffold to fail with "proPackageNotFound" in npx context
because pro/squads was missing from the published tarball.

Adds pro/squads/, pro/pro-config.yaml, pro/feature-registry.yaml,
pro/package.json, and pro/README.md to the files field.

Bumps version to 5.0.3.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: use temp dir in stepInstallScaffold test to prevent timeout

The test was passing a nonexistent path which caused the scaffolder
to hang when bundled pro/ dir was found locally.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: Pedrovaleriolopez