Two improvements to the build workflow: consolidate duplicated steps across build-* jobs using composite actions, and adopt a new OS/arch-aware naming scheme for release binaries with backward-compatible copies.

Composite actions

setup-r-for-build

Extracts the five setup steps (checkout, Pandoc, R, R deps, update.packages()) shared across all four build-* jobs. Also adds a post-checkout rm -f TinyTeX-*.* cleanup as a safety measure.

upload-bundles

Replaces all per-job nick-fields/retry@v3 upload steps. Dynamically discovers assets in the working directory and uploads them — no hardcoded filename lists:

# Patterns searched in working directory:
TinyTeX-*.*  installer-unix.tar.*  tinitex.*  texlive-local.deb  regex.tar.gz

Implements 5-attempt retry with 10 s back-off via a portable shell: bash loop (works on Windows via Git Bash). Each build-* job and tinitex now ends with:

- name: Upload bundles
  uses: ./.github/actions/upload-bundles
  with:
    draft-tag: ${{ needs.new-release.outputs.draft-tag }}

New binary naming scheme

Format: TinyTeX-{N}-{os}-{arch}.{ext}, where arch is omitted for windows/darwin:

All *nix archives use xz compression uniformly. Backward-compat copies are cp renames — tar xf auto-detects compression regardless of extension.

tinitex job

Added actions/checkout@v4 (required to resolve ./.github/actions/upload-bundles). Updated repackage step to place output files in the workspace root (mv ... ../..) so the upload composite action finds them without a cd tinitex/ workaround.

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