Migrate MDK from nostr-sdk 0.44 to 0.45

[erskingardner]

Summary

Move MDK from the Nostr 0.44 dependency line to nostr-sdk 0.45.

The 0.44 line remains usable for the immediate dependency update, but the standalone nostr-relay-pool and nostr-relay-builder crates have been folded into nostr-sdk in 0.45. Track the migration independently so routine 0.44 maintenance stays small and bisectable.

MDK migration work

• Replace direct nostr-relay-pool and nostr-relay-builder usage with the 0.45 SDK surface.
• Update transport-nostr-adapter::NostrSdkRelayClient notification handling from RelayPoolNotification to ClientNotification; preserve the split between trusted delivery and raw per-relay telemetry.
• Adapt subscription management to the redesigned API. In 0.45 relays no longer inherit pool subscriptions, so retain MDK's account-scoped subscriptions, group-route reconciliation, stale cleanup, and no-filter-leak behavior for one-shot publish relays.
• Adapt relay add/remove, relay access, connection lifecycle, fetch/query, publish, and unsubscribe calls to the redesigned client APIs.
• Replace signer-driven NIP-42 configuration with the 0.45 authenticator model while preserving per-account signer isolation and redacted error behavior.
• Update direct nostr types and features, including the removed SDK NIP feature flags.
• Refresh local relay tests and all adapter/app real-relay coverage; retain dial-safety, URL-redaction, telemetry, KeyPackage, kind-445, Welcome, and directory-query invariants.
• Regenerate and validate MarmotKit/UniFFI and the Android/iOS artifacts after the Rust migration.

Acceptance criteria

• No standalone nostr-relay-pool or nostr-relay-builder dependency remains.
• All Nostr adapter, peeler, app relay-runtime, and local relay E2E tests pass.
• Account/group subscriptions stay scoped to their intended relays and accounts; adding a one-shot publish relay exposes no read subscription.
• NIP-42 authentication remains per-account and does not expose relay URLs or key material in errors/logs.
• KeyPackage discovery, kind-445 delivery, Welcome delivery, directory queries, publishing, and reconnect/resubscribe behavior remain covered.
• just fast-ci, MarmotKit generation, and mobile artifact validation pass.

References

• Follow-up to Upgrade nostr-relay-pool to fix forged-event cache poisoning (RUSTSEC-2026-0224) #1218.
• nostr-sdk 0.45 release changelog: https://github.com/nostrdevkit/nostr/blob/ede118f4db5d8ec2a8b47e869220f7e723ed8775/nostr-sdk/CHANGELOG.md