Surfaced the SP7 T7 dispatch-arm bug at runtime (unknown-name panic at
fold boundary). This test enumerates RegistryEntry names from
StateResetRegistry::new() and asserts each has a match arm in
reset_named_state, catching the bug at `cargo test -p ml --lib`
instead of mid-training.
Source-introspection design — no production-code change. Test fails
fast if a future contributor adds a registry entry without the
corresponding dispatch arm.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>