feat(admin): show API request log storage stats

[chrarnoldus]

Summary

• show the exact api_request_log record count on the API Request Log admin page
• show total PostgreSQL relation size in MB, including indexes and TOAST storage
• preserve the existing oldest-entry age indication in the combined summary

Validation

• pnpm exec oxfmt apps/web/src/routers/admin-router.ts apps/web/src/app/admin/api-request-log/page.tsx
• pnpm exec oxlint --config .oxlintrc.json apps/web/src/routers/admin-router.ts apps/web/src/app/admin/api-request-log/page.tsx
• git diff --check
• tests deferred to CI as requested

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (2 files)

• apps/web/src/app/admin/api-request-log/page.tsx
• apps/web/src/routers/admin-router.ts

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_{Review guidance: REVIEW.md from base branch main}