Move relay admin panel to NIP-43 message path

[baxen]

Summary

• move relay access/admin membership reads to the relay message path via the NIP-43 kind:13534 snapshot
• publish relay membership admin changes as signed NIP-43 admin events over WebSocket (kinds 9030–9032)
• update onboarding membership checks and E2E mocks to use the same relay path
• ignore local identity.key files so dev identity secrets are not accidentally staged

Test plan

• cd desktop && pnpm exec tsc --noEmit
• cd desktop && pnpm exec biome check src/shared/api/relayMembers.ts src/features/relay-members/hooks.ts src/features/onboarding/ui/OnboardingFlow.tsx src/testing/e2eBridge.ts
• pre-commit / pre-push hooks passed, including desktop/web/mobile checks, Rust fmt/clippy/tests, desktop build, desktop Tauri check, and mobile tests

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Distinguish missing NIP-43 snapshot from denied membership

Returning an empty list when no kind 13534 event exists makes getMyRelayMembership() resolve to null, which onboarding interprets as “access denied” (checkMembershipDenied in OnboardingFlow.tsx). On relays with membership gating disabled, the server does not publish the startup 13534 snapshot, so this path incorrectly sends normal users to the membership-denied flow before profile save. Please treat “no snapshot available” as a non-denial state (or explicitly surface an unknown state) instead of collapsing it to “not a member.”

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