chore: map rocknix and retropie core names

ROCKNIX names its standalone packages <emu>-sa (package.mk under
projects/ROCKNIX/packages/emulators/standalone at 20261001); RetroPie
names its libretro scriptmodules lr-<name>. Each name joins the profile
of the project its package builds. supermodel-sa builds
DirtBagXon/model3emu-code-sinden, the supermodel3 profile.

emulators/gopher64.yml

@@ -9,6 +9,7 @@ core_version: "v1.1.42"
 display_name: "Nintendo - Nintendo 64 (gopher64)"
 cores:
   - gopher64
+  - "gopher64-sa"
 systems:
   - nintendo-64
 mode: standalone