Re-home network-call visualization as a SecurityLens panel

[CodeBuildder]

Context

Existing Argus network visualization refactored as a SecurityLens component for the Sentinel shell. Parent: #87.

Acceptance Criteria

• Argus exports a SecurityLens component mountable by the Sentinel unified shell
• Network-call visualization reads from world model topology API, not local state
• Lens renders threat findings overlaid on the network graph
• Standalone Argus app still works for local development

Dependencies

Blocked by: none | Blocks: none

Notes

No model tier. UI re-home.