Clarify VerifyAgent separation and runtime scope; update docs and server comment

[GsCommand]

Motivation

• Separate product/demo messaging from the execution runtime so the repo clearly represents the CommandLayer execution runtime responsibilities (receipt canonicalization, hashing, signing, and runtime endpoints) rather than hosting a public verifier UI/demo.
• Make it explicit that public paste-and-verify verification is handled by the external VerifyAgent repository while preserving all runtime cryptographic and ENS verification primitives.

Description

• Updated README.md to add explicit layer boundaries, a concise runtime receipt flow, and an external link to VerifyAgent at https://github.com/commandlayer/verifyagent for public paste-and-verify use cases.
• Added a separation note to CHANGELOG.md and added clarifying guidance to docs/OPERATIONS.md and docs/CONFIGURATION.md to emphasize that this repo is runtime-only and does not include the VerifyAgent product/UI/demo.
• Removed product-specific wording from a server comment in server.mjs (ENS resolution comment) while preserving the ENS-based verification logic and all receipt canonicalization, hashing, and Ed25519 signing/verification code.
• Files edited: README.md, CHANGELOG.md, docs/OPERATIONS.md, docs/CONFIGURATION.md, and server.mjs.

Testing

• Ran npm run check (syntax/check) and it succeeded with no errors.
• Ran npm test which executed unit tests and smoke flow and completed successfully (all tests passed: 28 tests total, smoke OK).
• Performed repo-wide grep scans for VerifyAgent/demo/verifier strings to confirm remaining references are only external links and documentation pointers, and those checks passed.

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Codex Task