ci: use go-react image toolchains instead of setup-go/setup-node

On the go-react runner image, npm/node/go already work (npm ci succeeds),
but the setup-go/setup-node actions install tool-cache binaries that can't
execute on this runner (node/22.22.3/x64: "cannot execute"), failing the
jobs in their post steps. Drop those actions and use the image's built-in
toolchains; also reduces flaky github.com action clones.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitea/workflows/ci.yaml

@@ -11,10 +11,6 @@ jobs:
     runs-on: go-react
     steps:
       - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
-        with:
-          node-version: 22
-          cache: npm
       - run: npm ci
       - run: npm run lint
       - run: npx tsc --noEmit
@@ -24,10 +20,6 @@ jobs:
     runs-on: go-react
     steps:
       - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
-        with:
-          node-version: 22
-          cache: npm
       - run: npm ci
       - run: npm test
 
@@ -36,10 +28,6 @@ jobs:
     runs-on: go-react
     steps:
       - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
-        with:
-          node-version: 22
-          cache: npm
       - run: npm ci
       - run: npm run build
       - name: Upload build artifacts