fix: align multilingual hero layouts

[recrack]

Summary

• share the corrected hero heading scale across all four locales
• pin the desktop product preview and heading to stable cross-locale anchors
• keep stacked layouts natural and cover the 1041px breakpoint edge
• extend the homepage regression contract

Test plan

• Full .githooks/pre-push (Python 10, Swift 335, samples, Headless, assets, site, Pages)
• Four locales at 320, 390, 768, 1040, 1041, 1080, 1120, 1200, and 1440px
• Zero horizontal overflow; zero desktop cross-locale heading/image-top spread
• shellcheck, actionlint, and git diff --check

Closes #17