r-dsl r-grf r-dicekriging: init pkgs

[bshor]

Add r-dsl (CRAN-style packaging of naoki-egami/dsl, Design-based
Supervised Learning by Egami, Hinck, Stewart, and Wei) along with its
two missing CRAN dependencies, r-grf and r-dicekriging.

dsl is not on CRAN and has no upstream tags/releases, so r-dsl is
pinned to upstream commit 537664a (master HEAD as of 2025-07-22) with
source: manual set to 0.1.0. The pin can be bumped if upstream
publishes a new commit or version.

Verification:

• git diff --check / git diff --check --cached
• python -m py_compile BioArchLinux/r-{dicekriging,grf}/lilac.py
• bash -n on all three PKGBUILDs
• makepkg --verifysource on all three
• makepkg -Cfd end-to-end build of all three (using temp R libraries
  for r-grf and r-dsl to satisfy in-PR dependencies)