v0.13.1

Volatility and Covariance, and the diagrams that had been quietly going missing.
Nothing is removed or renamed: every subpath published in 0.13.0 resolves
unchanged, and no entry point changed its name or signature.

	0.13.0	0.13.1
Topics	675	697
Domains	17	18
Topics whose arithmetic is asserted on every build	601	623
Topics with a validated api contract	675 / 675	697 / 697
Topics carrying their diagram source	301	692

New

• Volatility and Covariance — 22 topics. Historical estimators
  (close-to-close through Yang-Zhang), realized measures (realized variance and
  covariance, bipower variation, the jump-variation detector, the realized
  kernel), conditional volatility (ARCH, GARCH, EGARCH, GJR-GARCH, FIGARCH,
  HAR-RV) and covariance estimation (sample and EWMA, Ledoit-Wolf and oracle
  approximating shrinkage, factor-model and graphical-lasso). Each ships its own
  module, and all 22 have their numbers asserted here rather than taken on trust.

Fixed

• 369 topics were publishing no diagram source. Their Mermaid is written on
  Windows and therefore CRLF, and the fence that lifts it out matched a bare
  newline — so the extraction quietly returned nothing and the page rendered
  without the diagram it was written to have. Catalog Markdown is now read with
  its line endings normalised.

Internal

• The metadata reader learned two forms of YAML it had been refusing: a block
  sequence sitting at its parent key's own indent, and a plain scalar wrapped
  across lines. Both are valid, both are what the newer generators emit, and
  between them they were dropping everything below the first wrapped summary.
• A sixth fixture convention: a named case list, where each case pins a whole
  reference output, a subset of fields, or the error code a bad input must
  raise. It is the first shape that asserts the refusals as well as the numbers.