Actor Expansion

Add two new actor types — AI Agents and Users — with distinctive 3D meshes, realistic test data, and connection patterns that reflect modern network traffic.

• AgentMesh — IcosahedronGeometry (20 triangular faces), grounded Y-axis spin + hover bob, geodesic/crystalline appearance
• UserMesh — Composite sphere head + truncated cone body (person silhouette), slow grounded spin, matte finish
• Entity factory — 'agent' and 'user' cases added to createEntity()
• Tag helpers — at() for agent tags (Model, Framework, Owner, Autonomy), ut() for user tags (OS, Timezone, Location, Department, Role)
• Connection weights — Agent→vendor (0.5, LLM API calls), user→app (0.5), user→agent (0.4)
• New scenarios — aiTeamScenario (25 actors), userWorkspaceScenario (30 actors grouped by Department)
• AI vendor URLs — OpenAI, Anthropic, Hugging Face, Cohere, Replicate

• Users are dual-modeled — visible actor entity AND grouping context. Group by Department/Role creates user-context rugs using existing tag-based grouping (no special code needed).
• Agent geometry (Icosahedron) — visually distinct from App's dodecahedron (20 triangular vs 12 pentagonal faces). The faceted, crystalline look conveys synthetic intelligence.
• Hover bob for agents — subtle floating animation distinguishes agents from grounded services/users.

C13: Group Mode — the group-by-type mode, layout engine, entity system, transitions, and composable architecture carry forward.