Fix CI: drop unreachable external actions/* (data.forgejo.org timeout)

Replace actions/checkout, setup-go, upload-artifact with an inline git
clone and a committed packwiz binary (tools/packwiz), so the workflow
needs no outside network beyond the docker image pull and a clone from
the instance itself. Release step (tag-gated) unchanged.

.gitea/workflows/build-pack.yaml

@@ -10,22 +10,11 @@ jobs:
     runs-on: docker
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
-
-      - name: Setup Go
-        uses: actions/setup-go@v5
-        with:
-          go-version: '1.22'
-
-      - name: Install packwiz
-        run: go install github.com/packwiz/packwiz@latest
-
-      - name: Add packwiz to PATH
-        run: echo "$(go env GOPATH)/bin" >> "$GITHUB_PATH"
+        run: git clone --branch "${GITHUB_REF_NAME}" --depth 1 "https://x-access-token:${GITHUB_TOKEN}@git.mithraic.cloud/ad3laid3/FKRPG.git" "${GITHUB_WORKSPACE}"
 
       - name: Refresh index
         working-directory: client_pack
-        run: packwiz refresh
+        run: ../tools/packwiz refresh
 
       - name: Integrity check
         working-directory: client_pack
@@ -37,11 +26,11 @@ jobs:
 
       - name: Export client Modrinth pack
         working-directory: client_pack
-        run: packwiz modrinth export -o ../FKRPG-${GITHUB_REF_NAME}.mrpack --restrictDomains=false
+        run: ../tools/packwiz modrinth export -o ../FKRPG-${GITHUB_REF_NAME}.mrpack --restrictDomains=false
 
       - name: Refresh server index
         working-directory: server_pack
-        run: packwiz refresh
+        run: ../tools/packwiz refresh
 
       - name: Integrity check (server)
         working-directory: server_pack
@@ -53,15 +42,7 @@ jobs:
 
       - name: Export server Modrinth pack
         working-directory: server_pack
-        run: packwiz modrinth export -o ../FKRPG-SERVER-${GITHUB_REF_NAME}.mrpack --restrictDomains=false
-
-      - name: Upload pack artifacts
-        uses: actions/upload-artifact@v3
-        with:
-          name: fkrpg-pack
-          path: |
-            FKRPG-${GITHUB_REF_NAME}.mrpack
-            FKRPG-SERVER-${GITHUB_REF_NAME}.mrpack
+        run: ../tools/packwiz modrinth export -o ../FKRPG-SERVER-${GITHUB_REF_NAME}.mrpack --restrictDomains=false
 
       - name: Release
         if: startsWith(github.ref, 'refs/tags/v')