Allow schema preflight after atomic bootstrap identity creation #1693

Audit reference: Follow-up

What can go wrong

A brand-new node creates its Ethereum and libp2p identities before schema preflight. The preflight mistook those two bootstrap keys for legacy protocol state and stopped every fresh node with a missing-schema error.

When it happens

This happens on the first startup after atomic autowallet initialization, before actors or history replay begin.

What changed

Preflight now treats either an empty store or exactly one complete identity pair as fresh and stamps the current schema. Partial identities, extra keys, snapshots, or event-log records still fail closed, and the same rule is used by the storage validator.

Why the change works

Bootstrap identity is recognized narrowly without weakening upgrade safety: anything beyond the exact known pair still requires an existing schema marker.

Checks

Focused in-memory, Sled, validator, and actor-level startup tests pass.