feat(renderer): add three.js Scene Lab with orbitable torus knot

[simonhagger]

Summary

• New lazy Scene Lab route: three.js WebGL scene — wireframe torus knot + 900-point star field, OrbitControls (drag/zoom), directional lighting
• Spin/wireframe/pause are signals bridged via \�ffect(); rAF loop runs outside Angular change detection with live FPS
• Full GPU hygiene on destroy: geometry/material disposal, \controls.dispose(),
  enderer.dispose(), ResizeObserver disconnect

Validation

• Dev build green: \scene-lab-page\ lazy chunk 1.18 MB (three.js included); production budget unaffected — labs excluded from prod route set by design
• 
  enderer:test\ green incl. new create/teardown spec;
  enderer:lint\ clean after removing non-null assertions
• Dependency added: three ^0.185.1 (+@types/three dev)

Security Checklist

• Security review completed
• Threat model updated or N/A explained
• Confirmed no secrets/sensitive data present in committed files