fix(viewer): repair clean builds and Pages deployment

[ssrihari]

Summary

• add explicit setup, check, and test scripts for the analyzer, viewer, and CLI packages
• install the nested packages in CI instead of relying on pre-existing local dependencies
• upload viewer/dist, where the production build is actually emitted
• document the viewer/analyzer setup command

Why

After the analyzer/viewer split, a clean root install only provided Vite and Vitest. The viewer build could not resolve its own tooling or the analyzer's runtime dependencies, and the Pages workflow uploaded the obsolete root dist path.

Validation

• clean bun run setup:all
• bun run check
• bun run test (163 analyzer tests and 7 viewer tests passed; 7 analyzer tests skipped)
• bun run build
• verified viewer/dist/index.html and viewer/dist/404.html