fix: stabilize Pages validation

[yyyyaaa]

Summary

• keep the repository configured for GitHub Pages deployments through GitHub Actions
• stop coupling the phone resend countdown test to timers owned by TanStack Form internals
• verify the component-owned countdown timeout is cleared on unmount

Root cause

The first Pages run failed before building because Pages had not been enabled for this new repository. After enabling Pages and rerunning, validation exposed a nondeterministic assertion that counted every fake timer in the process. TanStack Form owns an unrelated one-second interval and transient timeout, so the expected global count was not stable.

Verification

• Blocks TypeScript check passed
• 1,080 unit tests passed
• focused phone-list test passed 20 consecutive runs
• static Pages export generated all 188 routes
• Pages artifact assembly assertions passed locally
• remote CI run 29383322800 passed
• all 16 Playwright visual tests passed

No npm publishing automation is added.