[ci] install extra LaTeX packages so Windows can build the PDF manual

[bburns632]

Problem

main has been red since #355 added the windows-latest job. R CMD check --as-cran fails at checking PDF version of manual:

* checking PDF version of manual ... WARNING
LaTeX errors when creating PDF version.
LaTeX errors found:
* checking PDF version of manual without index ... ERROR
* checking for non-standard things in the check directory ... NOTE
  'pkgnet-manual.tex'

The TinyTeX bundle that setup-tinytex installs on Windows is too minimal for Rd2pdf:

• Attempt 1 (with index) — pkgnet.Rcheck/pkgnet-manual.log shows a clean first pdflatex pass that stops immediately after Writing index file Rd2.idx (18 pages, vs. 19 on Linux). Check's LaTeX errors found: list is empty because the failure is outside pdflatex. That WARNING alone trips error-on: "warning".

• Attempt 2 — R retries with R_RD4PDF=times (see the "without index" branch of tools:::.check_packages). Dropping inconsolata makes times.sty fall back to Courier, and Rdlatex.log dies with:

  ! Font T1/pcr/m/n/10=pcrr8t at 10.0pt not loadable: Metric (TFM) file not found.
  Cannot find pcrr8t.mf.
  

Ubuntu and macOS pass because their bundles (plus apt texinfo on Ubuntu) already cover this.

Fix

release.yml already has an Install additional LaTeX Packages step, and its windows-latest (R devel) job passed the identical --as-cran check in run 31666781512. ci.yml never got the equivalent step. This mirrors it.

collection-fontsrecommended supplies the missing Courier metrics; inconsolata keeps the primary (non-fallback) path working.

Applied to all three OSes rather than gated on Windows, both to match release.yml and to avoid the same latent breakage if the Linux/macOS bundles shift.

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