Fix flaky e2e Tribute popup selection in CI

[bartekplus]

Summary

• make popup suggestion reads use the active focused input's tribute menu first, then visible menu fallback
• avoid brittle global .tribute-container li:first-child lookups that can target stale menus in CI
• dispatch mousedown/mouseup/click for suggestion selection to match Tribute menu handling
• keep deterministic post-click wait for inserted text

Validation

• CI=true npm run test:e2e (pass)
• CI=true npx jest --config=jest-e2e.config.ts tests/e2e/puppeteer-extension.test.ts -t 'Prediction popup appears in #test-contenteditable when typing and prediction is inserted on TAB' --runInBand (12/12 passes)