Adds three com.atproto.identity.* endpoints that previously fell through to the AppView proxy and returned 501: - resolveDid: returns the local DID document for our DID - resolveIdentity: returns {did, handle, didDoc} for our DID or handle - getRecommendedDidCredentials: returns rotation keys, alsoKnownAs, verification methods, and PDS service entry for inbound migration Foreign DIDs and handles still fall through to the AppView proxy.