docs: add marimo notebooks to the companion book

[tschm]

What

Three self-contained marimo notebooks under book/marimo/notebooks/, wired into the companion book (exported to docs/notebooks/*.html by make book and linked from a new Notebooks nav section). Layout follows the jebel-quant/jquantstats convention.

notebook	covers
01 — Active-set methods	The active-set / block-principal-pivoting loop for min_{x≥0} ½x'Ax − b'x: KKT/LCP conditions, the reduced free-set solve, the primal/dual violator tests, and the least-index Bland fallback that guarantees finite termination. Interactive solve with a free-set trajectory heatmap.
02 — Equality constraints	solve_nnqp vs solve_nnqp_eq: the multiplier λ, the saddle system, the p×p Schur complement, the shifted reduced gradient s = Ax − b − Bᵀλ, and the p=1 simplex/budget case with a live slider.
03 — Test problems	Documents tests/problems.py: the plant-a-known-optimum recipe, make_problem, make_eq_problem, make_adversarial (forces the fallback — 19/40 seeds), and make_scaled_problem (CG vs Jacobi-PCG).

How it hooks into the build

• Each notebook carries a PEP 723 header with [tool.uv.sources] nncg = { path = "../../..", editable = true }, so the synced _book-notebooks target (marimo export html --sandbox) resolves the local package. Notebook 03 locates the repo root at runtime so its tests.problems import works under the sandbox cwd.
• marimo>=0.18.0 added to the dev dependency group (which is in default-groups) so uv run marimo resolves — the empty dev group would otherwise break make book.
• mkdocs.yml: new Notebooks nav section.

Verification

• make book builds end-to-end; all three notebooks export and appear in _book/notebooks/ and the nav.
• All three execute cleanly under marimo export html --sandbox (the exact book path).
• ruff check and ruff format --check pass; full pre-commit hook suite green.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Adds three self-contained Marimo notebooks to the project’s companion MkDocs book, including wiring them into the site navigation and ensuring the book build can export the notebooks to standalone HTML.

Changes:

• Add marimo>=0.18.0 to the dev dependency group (and lockfile) so the book’s notebook export tooling resolves.
• Add a new Notebooks section to mkdocs.yml that links the exported HTML pages.
• Introduce three new Marimo notebook scripts under book/marimo/notebooks/.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
uv.lock	Locks marimo and its transitive dependencies; updates dev metadata to include the dev group.
pyproject.toml	Adds marimo>=0.18.0 to the dev dependency group used by the book build.
mkdocs.yml	Adds a Notebooks nav section linking to exported HTML notebook artifacts.
book/marimo/notebooks/01_active_set_methods.py	New Marimo notebook documenting the active-set/BPP/Bland fallback path.
book/marimo/notebooks/02_equality_constraints.py	New Marimo notebook documenting the equality-constraint (Schur complement) solver path.
book/marimo/notebooks/03_test_problems.py	New Marimo notebook documenting/using test problem generators and solver behavior.

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