P3: Enhance dashboard with live status, run monitoring, and findings chart

[Shreyas582]

Description

The API server dashboard at / serves a single static HTML page (api_server/src/dashboard.html). It does not auto-refresh, does not show live run progress, and cannot be used to trigger or monitor investigations.

Proposal

Enhance the dashboard with:

1. Auto-refresh: Poll /api/v1/health and /api/v1/runtime/status periodically
2. Run list: Show recent/active runs from /api/v1/runs with status badges
3. Case view: List open cases with finding counts
4. Findings chart: Simple severity distribution chart (JS-based, no framework needed)
5. WebSocket support (stretch): Live streaming of run progress

This would make the API server useful as a lightweight monitoring console for security operations.

Affected Files

• api_server/src/dashboard.html (UI enhancements)
• api_server/src/routes.rs (potentially new SSE/WebSocket endpoint)