[UI] Build "Alert History" Table for Dashboard

[mijinummi]

Title: [UI] Build "Alert History" Table for Sentinel Dashboard

📝 Description

The Sentinel Dashboard needs a place to show past alerts. This issue focuses on the frontend table where users can view the history of detected threats.

🎯 Goal

Build a clean, responsive React table in apps/dashboard that displays a list of past "Watchdog Events."

✅ Requirements

• Table columns: Timestamp, Chain, Severity, Description.
• Color-coded severity tags (Red for High, Yellow for Medium).
• Simple "Filter by Chain" dropdown.

🛠 Technical Specs

• Difficulty: Easy
• Labels: good-first-issue, frontend, UI/UX