Fix declarative shadow root attribute

[danilutkin]

Summary

• extend the static site builder with glossary popovers, declarative shadow DOM cards, and speculation rules support while refreshing the shared stylesheet
• update existing posts to use inline glossary annotations that render through the Popover API
• regenerate the published HTML to ship encapsulated post cards and instant-navigation speculation scripts
• fix declarative shadow DOM templates to use shadowrootmode="open" so the blog cards render inside their shadow roots

Testing

• python3 build.py

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https://chatgpt.com/codex/tasks/task_e_68f01cbafd68832e909738963ad79d82