fix: prepare Prisma before solution tests

[kentcdodds]

Summary

• run workshop test preparation after dependency installation so Prisma clients are generated for all 54 apps
• skip browser and playground setup that the Vitest CI job does not need
• run every test in each completed Vitest-backed solution, excluding intentional intermediate-step failures and Playwright-only exercises from the incompatible runner
• fix the completed database solution test so its nested route renders instead of being replaced by a placeholder root component
• run tests on supported Node 22 because the pinned MSW/Undici stack has an AbortSignal realm incompatibility on Node 26; cross-platform setup validation remains on Node 26

Verification

• SKIP_PLAYWRIGHT=true SKIP_PLAYGROUND=true npm run setup:custom
• CI=true node ./epicshop/test.js '4.4.s,5.2.s,6.2.s,7.2.s,8.3.s,9.3.s,10.1.s,11.3.s'