Revise scipy notes to the literate memoir pattern

[dbosk]

Part of the notes-revision effort (see the tracking issue for the full
per-deck workflow: literate contents.nw conversion, memoir notes,
narrative prose, pedagogical restructuring, \ltnote{} annotations,
LaTeX semantics, LO labels, review).

Decks

modules/scipy/slides

• Literate conversion (contents.nw, chunks replace \inputminted
  line ranges, Makefile + gitignore)
• Memoir notes.tex
• Narrative prose (notes read standalone)
• Pedagogical restructuring (try-first, examples first, variation
  theory)
• \ltnote{} annotations + ltnotes.bib
• LaTeX semantics pass
• Mnemonic LO labels in abstract.tex
• Build + review pass

modules/scipy/slides-matlab

• Literate conversion (contents.nw, chunks replace \inputminted
  line ranges, Makefile + gitignore)
• Memoir notes.tex
• Narrative prose (notes read standalone)
• Pedagogical restructuring (try-first, examples first, variation
  theory)
• \ltnote{} annotations + ltnotes.bib
• LaTeX semantics pass
• Mnemonic LO labels in abstract.tex
• Build + review pass