feat(ml): compare convex solvers across scratch and SOTA (#17960)

* feat(ml): compare convex solvers across scratch and SOTA

See #16061

Co-Authored-By: Claude-Code <noreply@anthropic.com>

* fix(ml): keep measured LOC counts out of notebook prose

See #16061

Co-Authored-By: Claude-Code <noreply@anthropic.com>

* fix(ml): render exercise guidance as body text

Co-Authored-By: Claude Code <noreply@anthropic.com>

* fix(ml): describe SMO timing variation accurately

Re-execute the B.8 notebook after correcting its printed interpretation of measured timings. Papermill executed all 14 code cells successfully.

Co-Authored-By: Claude-Code <noreply@anthropic.com>

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Co-authored-by: Claude-Code <noreply@anthropic.com>

Author: jsboige