Change yarn for npm on config file for gh actions

Author: diguifi

.github/workflows/deploy-itch.yml

@@ -22,26 +22,17 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: 22
-          cache: yarn
-          cache-dependency-path: client/yarn.lock
-
-      # GitHub runners ship Yarn 1 at /usr/local/bin/yarn, which shadows Corepack.
-      - name: Enable Corepack (Yarn 4)
-        working-directory: .
-        run: |
-          sudo rm -f "$(command -v yarn)" "$(command -v yarnpkg)" || true
-          corepack enable
-          corepack prepare yarn@4.5.1 --activate
-          yarn --version
 
+      # Avoid Yarn/Corepack on the runner (global Yarn 1 conflicts with packageManager).
+      # npm is enough here — we only need a production webpack build.
       - name: Install dependencies
-        run: yarn install --immutable
+        run: npm install
 
       - name: Build
         env:
           # itch.io hosts static files only — connect to the live Deno game server
           WS_URL: wss://tiny-land.diguifi.deno.net/ws
-        run: yarn build
+        run: npm run build
 
       - name: Install Butler
         working-directory: .