🎨 Palette: Make OSINT modal trigger accessible for keyboard and screen reader users

[0m364]

💡 What:
Added role="button" and aria-haspopup="dialog" to the #sitrep-btn elements across concepts.html, contact.html, and products.html. Also updated modal.js to trigger the modal via the Spacebar key.

🎯 Why:
The OSINT trigger was using a native <a> tag with href="#". Native links do not respond to the Spacebar key like native <button>s do, leading to a broken expectation for keyboard users. Additionally, without the role="button", screen readers announce it as a "link" rather than an interactive control that opens a dialog.

📸 Before/After:
Before: Pressing Spacebar while focused on the OSINT button scrolled the page down.
After: Pressing Spacebar intercepts the scroll (e.preventDefault()) and opens the Situation Report modal exactly as the Enter key or a mouse click does.

♿ Accessibility:

• Screen readers now correctly announce the control as a button that opens a dialog.
• Keyboard-only users have full parity with mouse users, as both Enter and Spacebar keys function predictably for the control.

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PR created automatically by Jules for task 2923901992737797505 started by @0m364

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