Add an audit trail with optimistic UI and rollback for role assignment mutations

[Lakes41]

Difficulty: Advanced
Type: feature

Background
POST /v1/members/:address/roles is a Bearer-authenticated admin mutation (per the Live API endpoints table) that assigns a role to a member, and the app already uses React Query for data fetching/mutations.

Problem
Role assignment currently likely waits for the network round-trip before updating the UI (or, if optimistic, has no visible history of who changed what and when), and any failure handling/rollback behavior isn't documented — admins have no way to see a history of role changes made through the dashboard.

Expected outcome
Assigning a role updates the UI immediately (optimistic update via React Query's onMutate), automatically rolls back cleanly on failure (including on a 401 that isn't resolved by the auto-retry flow), and a local "recent changes" panel shows a short audit trail (who/what/when) of role changes made in the current admin session.

Suggested implementation

• Implement the mutation with React Query's optimistic update pattern: snapshot the previous member/role state in onMutate, apply the optimistic change, and roll back in onError.
• Add a lightweight, session-scoped (not necessarily persisted) audit log of role changes attempted in the UI, including failed/rolled-back attempts marked as such.
• Integrate with the existing SIWE re-auth retry flow (if implemented) so a 401-triggered rollback doesn't falsely mark a change as permanently failed if it's about to be retried.
• Add tests (mocking the API layer) for: successful optimistic update, network failure rollback, and 401-then-retry-success.

Acceptance criteria

• Role changes reflect optimistically in the UI before the network call resolves
• Failed mutations roll back the optimistic change and are clearly marked in the audit panel
• Audit panel shows a readable history of attempted role changes for the current session
• Tests cover success, failure/rollback, and 401-retry-success paths

Likely affected files/directories

• app/admin/ (role assignment UI)
• lib/api/live.ts, lib/api/mock.ts
• lib/wallet/providers.tsx

[EngrEOOnoja]

I'd like to take this on. I'll implement the optimistic role-assignment mutation with snapshot/rollback via React Query's onMutate/onError, add a session-scoped audit panel showing role-change history including failed/rolled-back attempts, and carefully integrate with the SIWE re-auth retry flow so a 401 that's about to succeed on retry isn't falsely marked as a permanent failure with tests covering success, hard failure, and 401-then-retry-success paths.

[grantfox-oss]

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Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #332)
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