[codex] Retry Friendbot funding setup

[Dreamstore2046]

Summary

• retry Friendbot funding for transient 429/5xx/network failures with exponential backoff, up to five attempts
• fail fast on permanent Friendbot validation errors with a clear permanent HTTP <status> message
• write .setup-wallets-checkpoint.json after each funded/already-existing wallet so reruns skip completed wallets
• document the checkpoint behavior and ignore the local checkpoint file

Validation

• npm test -- scripts/__tests__/setup-wallets.test.ts
• npx tsc --noEmit --target ES2022 --module ESNext --moduleResolution bundler --allowImportingTsExtensions --esModuleInterop --allowSyntheticDefaultImports --strict --skipLibCheck --types node,vitest scripts/setup-wallets.ts scripts/__tests__/setup-wallets.test.ts
• git diff --cached --check

Closes #201.

[vercel]

@Dreamstore2046 is attempting to deploy a commit to the Harrison Eze's projects Team on Vercel.

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[overprodigy]

Closing in favor of unified PR addressing all issues