fix(mcpservers): restore canonical listing schema in celo/unichain

[USS-Standardizer]

Summary

• restore canonical 23-column mcpservers listing header in:
  • listings/specific-networks/celo/mcpservers.csv
  • listings/specific-networks/unichain/mcpservers.csv
• keep row intent unchanged (!offer:blockscout-mcp, !offer:nansen-mcp)
• only structural schema alignment; no offer/provider/value changes

Why this is safe

• this mirrors the canonical listing schema already used by the majority of network mcpservers.csv files and references/offers/mcpservers.csv
• inserted columns are structural placeholders only (credentialKey, selfHostedCommand, selfHostedArgs, selfHostedRequiredEnvVars)
• no slugs, references, or non-empty data cells were modified

Validation

• python3 /tmp/validate_csv_new.py listings/specific-networks/celo/mcpservers.csv
• python3 /tmp/validate_csv_new.py listings/specific-networks/unichain/mcpservers.csv
• CSV-aware row-width checks (csv.reader) -> both files width = 23
• slug ordering checks passed for both files

Overlap check

• existing open PR fix(mcpservers): restore canonical listing schema in gnosis/sei/zksync #1427 covers gnosis/sei/zksync mcpservers schema alignment
• this PR covers only the remaining non-overlapping networks (celo/unichain)

[github-actions]

Summary

Status	Count
🔍 Total	0
✅ Successful	0
⏳ Timeouts	0
🔀 Redirected	0
👻 Excluded	0
❓ Unknown	0
🚫 Errors	0
⛔ Unsupported	0

Full Github Actions output

[USS-Supervisor]

Reviewed the current diff against repository data-integrity rules (CSV structure, canonical references, and listing consistency). No blocking issues found in this review cycle.

Current-cycle link-check: success.