[SC] Oracle admin rotation without contract redeploy

[Cbiux]

Summary

Implement admin rotation for the score-registry oracle — extend #27 pause with transfer_admin(new_admin) so production keys can be rotated without redeploying the contract.

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Background

#27 added pause/unpause. Production still needs a safe path to rotate ORACLE_SECRET_KEY / admin address when keys are compromised or team members change.

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Proposed contract API

File: Contracts/score-registry/src/lib.rs

pub fn transfer_admin(env: Env, new_admin: Address) {
    let admin = /* current admin */;
    admin.require_auth();
    env.storage().instance().set(&ADMIN_KEY, &new_admin);
    // emit AdminTransferred event
}

Two-step variant (recommended):

pub fn propose_admin(env, candidate: Address)  // stores pending
pub fn accept_admin(env)                       // candidate.require_auth()

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Server changes

• Admin CLI script: scripts/rotate-oracle-admin.ts
• Document rotation runbook in Docs/vercel-deploy.md

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Acceptance criteria

• transfer_admin or two-step flow implemented
• Only current admin can initiate
• Unit tests for happy path and unauthorized caller
• Event emitted on successful rotation
• Runbook documented (no secrets in git)
• Pause must be active during rotation (optional safety)

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Related

• [SC] Oracle security: admin rotation and emergency pause #27 pause (closed)
• Deploy score-registry Soroban contract to Stellar testnet #16 deployment
• Provision production MySQL and configure DATABASE_URL on Vercel #15 production ops

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Out of scope

• Multi-sig admin
• On-chain admin timelock

[snkk2x-collab]

/attempt #66

[Cbiux]

Cerrado: duplicado de capacidades ya en score-registry (admin/pause). Backlog = 12 issues.