🎨 Palette: Improve keyboard and screen reader accessibility for modal triggers

[0m364]

💡 What: Added role="button", aria-haspopup="dialog", and a keydown event listener to handle the Spacebar key for the "OSINT" <a href="#" id="sitrep-btn"> anchor tags. Also explicitely added an e.preventDefault() inside the listener.

🎯 Why: To ensure that assistive technologies like screen readers announce the anchor triggers as buttons instead of links, and to polyfill standard button behavior so that keyboard users can use the Spacebar to trigger the modal rather than relying solely on the Enter key.

📸 Before/After: Visual changes are not applicable as this was a semantic HTML markup and JavaScript logic improvement.

♿ Accessibility: Ensures that pseudo-buttons built with anchor tags meet the expectations of users relying on screen readers and keyboard navigation.

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PR created automatically by Jules for task 12921593854475677702 started by @0m364

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