Preview Artifacts, Bridge Recovery & Prefab Workflows

Added reproducible animation preview artifacts with stored records and comparison tools for repeatable QA.Improved Unity bridge recovery during reloads/recompiles, added retry hints and safer timeout handling.

Added real Unity E2E animation fixtures and reorganized the test suite.Finished the v0.1.3 release, refreshed the README/docs, and started v0.1.4 prefab workflows.

Added inspect_prefab_asset and inspect_prefab_overrides with native Unity services, support for nested/variant/model prefabs, structured override inspection, stable IDs, and Python/integration/EditMode test coverage.