Add judge-friendly comments for ENS, verification, and receipt generation in server.mjs

[GsCommand]

Motivation

• Make it trivial for ETHGlobal sponsor judges to find the exact integration points for ENS-based signer lookup, runtime-core verification, receipt generation, and schema validation via clickable source-line links without changing behavior.

Description

• Inserted a comment above the ENS resolver call in server.mjs where fetchEnsSignerBundle is invoked to mark the ENS signer resolution (resolves cl.sig.pub / cl.sig.kid).
• Inserted a comment above the verifyReceiptEd25519Sha256 call in server.mjs to mark the CommandLayer receipt verification (canonical hash + Ed25519 signature verification).
• Inserted a comment above makeReceipt(...) in server.mjs to mark CommandLayer receipt generation (signing of execution receipts).
• Inserted a comment above the optional AJV schema validation block in server.mjs to mark receipt schema validation for verifiable agent receipts.

Testing

• Ran npm run check (which runs node --check server.mjs) and it completed successfully.

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Codex Task