Fix as never test casts and add --page-name whitespace normalization

[Copilot]

Three issues flagged in code review on the org:commerce:troubleshoot:deploy command:

• Test config stubs used as never, defeating TypeScript's structural checks on mock Configuration objects.
• --page-name was forwarded raw to the deployer without trimming, allowing whitespace-only values through despite the flag being required.

Changes

• Tests: Import Configuration type and replace as never with as Configuration on both config stub callsites — compiler now catches mock/shape drift.
• Command: Run flags.pageName through readString() (trims + returns undefined for blank) and add a this.error() guard, consistent with how organizationId and accessToken are already validated:

const hostedPageName = readString(flags.pageName);

if (!hostedPageName) {
  this.error('Missing page name. Provide a non-empty value for --page-name.');
}

---

🔒 GitHub Advanced Security automatically protects Copilot coding agent pull requests. You can protect all pull requests by enabling Advanced Security for your repositories. Learn more about Advanced Security.