feat: expose authenticator management via UniFFI

[agentotto]

cc @Dzejkop

Summary

Exposes the current world-id-core authenticator management APIs through WalletKit's UniFFI surface:

• Authenticator::insert_authenticator(...)
• Authenticator::update_authenticator(...)
• Authenticator::remove_authenticator(...)
• Authenticator::poll_gateway_request_status(...)

This is a fresh implementation on top of latest main; it does not reuse the stale approach from #306. The wrapper delegates protocol semantics/signing/commitment updates to world-id-core 0.10.2, whose authenticator-management behavior reflects worldcoin/world-id-protocol#673.

Semantics

• Insert/update/remove return a gateway request ID and do not mutate local packed_account_data.
• Insert accepts the new authenticator's compressed EdDSA public key as the protocol Uint256 representation and its on-chain signer address as a hex string.
• Update/remove require the caller-provided pubkey_id slot, matching the protocol API.
• A generic gateway polling method is exposed so consumers can wait for finalization and then initialize/re-initialize authenticators as needed.

Validation

• cargo fmt --all
• cargo test -p walletkit-core authenticator::tests --no-default-features
• cargo check -p walletkit-core --no-default-features
• cargo check -p walletkit-core
• cargo clippy -p walletkit-core --no-default-features -- -D warnings
• cargo clippy -p walletkit-core --no-default-features --tests -- -D warnings

Note: cargo test -p walletkit-core authenticator::tests with default features currently fails on main because walletkit-core/src/issuers/recovery_bindings_manager.rs imports cache_embedded_groth16_material in tests without enabling the embed-zkeys feature; this is unrelated to this change.

---

Note

Medium Risk
Exposes new key-management operations (insert/update/remove authenticators) and changes the public gateway status enum shape, which can affect downstream clients and has on-chain side effects if misused.

Overview
Adds UniFFI-facing authenticator-management APIs on Authenticator for insert_authenticator, update_authenticator, and remove_authenticator, plus a generic poll_gateway_request_status to wait for gateway/on-chain finalization.

Replaces the registration-only RegistrationStatus with a shared GatewayRequestStatus enum that carries tx_hash for Submitted/Finalized, updates InitializingAuthenticator::poll_status and the CLI registration polling to use it, and re-exports the new enum from walletkit-core.

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[agentotto]

Follow-up update pushed in e94efb5:

• Removed the separate UniFFI RegistrationStatus enum.
• Re-exported and use GatewayRequestStatus as the single generic gateway status type.
• Updated InitializingAuthenticator::poll_status() to return GatewayRequestStatus.
• Updated walletkit CLI registration polling call sites to match GatewayRequestStatus::Finalized { .. } / Failed { .. }.

Additional validation:

• cargo test -p walletkit-core authenticator::tests --no-default-features
• cargo check -p walletkit-core --no-default-features
• cargo check -p walletkit-cli --no-default-features
• cargo check -p walletkit-core
• cargo clippy -p walletkit-core --no-default-features -- -D warnings
• cargo clippy -p walletkit-cli --no-default-features -- -D warnings
• cargo clippy -p walletkit-core --no-default-features --tests -- -D warnings
• cargo test -p walletkit-cli --no-default-features