Add interactive 3D fleet visualization

[nahiyankhan]

Summary

• Adds ghost viz command that launches a local HTTP server serving an interactive Three.js 3D visualization of fleet fingerprints
• PCA projects 64-dim embeddings to 3D space; each fingerprint rendered as a particle cluster with pairwise distance lines and centroid marker
• Hover/click interaction with dimension breakdown panel, color-coded by cluster membership or dominant palette color
• Exports DIMENSION_RANGES from ghost-core for viz consumption

Test plan

• Generate 3+ fingerprints via ghost profile and run ghost viz fp1.json fp2.json fp3.json
• Verify browser opens with 3D scene, particle clusters at distinct positions
• Verify hover shows fingerprint IDs, click isolates and shows dimension breakdown
• Verify pairwise lines and centroid marker render correctly
• Verify --no-open and --port flags work
• Verify pnpm build succeeds and copies src/viz/ to dist/viz/

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