v2.2: Network map improvements and OS filtering

- Fixed jumpy network map: nodes settle in 2 seconds and stay fixed
- Added click vs drag detection for better node interaction
- Made legend clickable as OS type filters (Windows, Linux, macOS, etc.)
- Multiple filters can be active simultaneously (OR logic)
- Added 'Clear filters' button when filters are active
- Added DELETE endpoints to clear network hosts from dashboard
- Fixed nmap parser to only include hosts with open ports
- Nodes stay in place after dragging

services/dashboard/requirements.txt

@@ -3,3 +3,4 @@ uvicorn[standard]==0.32.1
 httpx==0.28.1
 pydantic==2.10.2
 jinja2==3.1.4
+websockets==12.0