numodel-bundle v0.6.0

Highlights
----------
* New per-prefix accessor \<prefix>steps expands to the iteration count N
  after \computemodel.  No more deriving N by hand from Tmax/dt.
* \mstep{<Name>}{<i>} now raises a numodel error when <i> is outside the
  recorded range, instead of silently expanding to nothing.
* \textmodel: alias keys (alias, aliasleft, aliasright) now work with
  amsmath dots macros (\cdots, \ldots, \dotsb, ...).  Fixes a regression
  introduced in v0.4.0 by the tabularray migration.
* \graphicmodel auto-layout no longer leaves an empty row between the
  stocks row and the constants row when the model has no auxiliary
  variables.

Build / packaging changes
-------------------------
* The user manual moved out of the .dtx into stand-alone
  numodel-manual.tex / numodel-plot-manual.tex.  The .dtx is now pure
  docstrip source.  Manuals use Arial + Lete Sans Math + Fira Mono and a
  tcolorbox+listings example environment so each example is shown
  verbatim and executed from a single source.
* The examples/ directory is no longer shipped to CTAN.

Removed
-------
* numodel: stockwidth setup key and \halfstockwidth macro (dead code).

See numodel/CHANGELOG.md and numodel-plot/CHANGELOG.md for the full list.