ci: allow workshops without a typecheck script

[kentcdodds]

Summary

• run Setup typechecking with npm's --if-present flag
• run the Playwright solution-test lane on Node 22 because Playwright 1.51 hangs under Node 26
• retain Node 26 validation across the Ubuntu, Windows, and macOS Setup matrix
• make the router test wait for a real pathname-based ship link instead of clicking a temporary href="#" placeholder
• preserve lint, solution-test, and deploy coverage

Verification

• git diff --check
• Prettier checks for changed workflow/test files
• root lint passes
• npm run typecheck --if-present exits successfully when no script exists
• reproduced Playwright 1.51 Chromium extraction and test-runner hangs under Node 26
• first solution Playwright test passes under Node 22
• prior CI run passed 16 of 17 solution apps and exposed the router placeholder race now fixed
• CI exercises Setup across Ubuntu, Windows, and macOS plus all solution tests

Context

The main deploy run failed all Setup matrix jobs solely because npm run typecheck exited with “Missing script: typecheck.” Iterating the newly enforced Test job also surfaced Playwright's Node 26 incompatibility and a deterministic test race against Suspense placeholders.