perf(cmdb): plan large-scale graph level-of-detail mode

[alexandervazquez98]

Problem

The visualizer needs to scale toward thousands of CIs across many clusters without rendering all detail at once.

Proposed Solution

Design and implement a level-of-detail mode:

• default cluster-only overview;
• render CIs only for focused/expanded clusters;
• aggregate or sample dense clusters;
• draw detailed links only on hover/click/focus.

Acceptance Criteria

• Initial view remains fluid for large CI counts.
• Cluster summaries remain useful when individual CIs are not rendered.
• Detail is available on demand without overwhelming the canvas.