[SandObserver]

Summary

• Assert work counts instead of elapsed time: rows scanned in the badge filter test, list entries read and key listings in the two aliased import tests (through a counting proxy).
• Run the hold test in latest on mocked setTimeout and Date instead of a 20 ms wall-clock bound.
• Add test-support/no-such-host.js, which answers every lookup with ENOTFOUND, and use it in the four tests that looked up nonexistent names over real DNS.
• Check the URL scheme in pingUnchecked before resolving the host, so a refused URL makes no DNS query. Add a test for it.
• Wait until the System Summary frame has its zoom applied before measuring boxes.
• Set a 20 minute globalTimeout on the Playwright suite.

Testing
All green. Each new count fails when its guard is removed. The backend suite passes with DNS answering nothing, apart from the resolver tests that start their own DNS server. The System Summary spec passed 50 of 50 runs in WebKit.

Changelog

Checklist

• Stays within the project constraints: one container, no runtime dependencies, no build step (see CONTRIBUTING.md).
• Tests added or updated for new logic, and the full suite, lint, and typechecks pass.
• Docs updated if behavior or configuration changed.