feat(scientific-studio): MATLAB-inspired matrices, solver, and plots

Summary

Adds src/scientific-studio/ — matrix ops, linear solver, plot canvas, command console. No LIVE MATLAB Runtime.

DOCUMENTED vs LIVE

See src/scientific-studio/README.md — honest comparison; no fabricated LIVE access.

Test plan

• cd src/scientific-studio && npm ci && npm test && npm run build (4 tests)
• Smoke the UI