🎨 Palette: Improve OSINT modal trigger accessibility

[0m364]

💡 What: Added role="button" and aria-haspopup="dialog" to all instances of the #sitrep-btn link. Implemented a keydown listener in modal.js to trigger the modal when the Spacebar is pressed while the button is focused.
🎯 Why: Using an anchor tag (<a>) as a button creates an accessibility gap. Screen reader users need to be informed that the element behaves like a button (and opens a dialog), and keyboard users expect it to respond to the Spacebar key (which <a> tags do not do natively).
📸 Before/After: N/A (Non-visual change).
♿ Accessibility: Fixed a critical interaction bug for keyboard users and improved semantic announcements for screen readers.

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PR created automatically by Jules for task 9647650749021884587 started by @0m364

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