refactree

Make refactoring implementation more exhaustive, complete and stable by fuzzing mv on repositories in the wild with isolated project checks via the internal/fuzzy harness (go test, not rft CLI).

Run real-world ingest invariant checks via the internal/fuzzy harness (go test), then curate failures into testdata/ingest fixtures.

Maintain `refactree` ingestor test fixtures under `testdata/ingest/`. Use when adding fixture cases, updating fixture source files, editing `expected.json`, or checking whether ingestor fixtures follow the repo standard.

Teach the model how to use refactree, a CLI tool for structural refactoring and symbol querying.