🎨 Palette: Improve accessibility for anchor buttons

[0m364]

💡 What: Added role="button" and aria-haspopup="dialog" to the #sitrep-btn anchor tags across concepts.html, contact.html, and products.html. Also updated the event listener in modal.js to allow keyboard users to trigger the modal using the Space key, preventing the default page scrolling behavior. Added a learning entry to .Jules/palette.md for this accessible anchor pattern.

🎯 Why: While native <button> tags respond to both Enter and Space keys, native <a> tags only trigger on Enter. When using anchors as buttons (e.g. href="#"), keyboard users and screen readers expect them to respond to Space. Adding the proper ARIA roles and a dedicated keydown handler ensures consistent, expected behavior for assistive technologies.

📸 Before/After: No visual changes. This is purely an accessibility improvement that enhances keyboard navigation and screen reader semantics.

♿ Accessibility: The role="button" ensures screen readers announce the element correctly, and the Space key event listener provides the expected interaction pattern for keyboard users, preventing frustrating page scrolling when trying to open the modal.

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PR created automatically by Jules for task 8932448095008489918 started by @0m364

[google-labs-jules]

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