CI: install devkitPro on runner instead of nested docker

Nested docker run broke under act (empty /work, no Makefile). Use official
install-devkitpro-pacman + dkp-pacman switch-dev on ubuntu-latest.

Made-with: Cursor

.github/workflows/build.yml

@@ -12,20 +12,31 @@ jobs:
     permissions:
       contents: read
 
+    env:
+      DEVKITPRO: /opt/devkitpro
+
     steps:
       - name: Checkout
         uses: actions/checkout@v4
 
-      # Build inside devkitPro image only. A job-level container would run every
-      # step there and break actions/checkout (needs Node). Same issue with `act`.
-      - name: Compile (Switch .nro)
+      # Install toolchain on the runner (no nested docker). Nested `docker run -v
+      # "$GITHUB_WORKSPACE"` fails under act: the mount points at an empty path.
+      - name: Install devkitPro
         run: |
-          docker run --rm \
-            -v "${{ github.workspace }}:/work" \
-            -w /work \
-            -e DEVKITPRO=/opt/devkitpro \
-            devkitpro/devkita64:latest \
-            bash -lc 'make -j$(nproc)'
+          set -euo pipefail
+          wget -q -U "dkp-apt" -O ./install-devkitpro-pacman https://apt.devkitpro.org/install-devkitpro-pacman
+          chmod +x ./install-devkitpro-pacman
+          yes | sudo ./install-devkitpro-pacman
+          sudo dkp-pacman -Sy
+          sudo dkp-pacman -S switch-dev --noconfirm
+
+      - name: Add devkitPro tools to PATH
+        run: |
+          echo "/opt/devkitpro/devkitA64/bin" >> "$GITHUB_PATH"
+          echo "/opt/devkitpro/tools/bin" >> "$GITHUB_PATH"
+
+      - name: Compile (Switch .nro)
+        run: make -j$(nproc)
 
       - name: Upload .nro artifact
         uses: actions/upload-artifact@v4