ci: fix EL_HOME to use lang/ subdirectory for El repo clone

El repo is organized under lang/ — runtime and dist/platform binaries
are at lang/el-compiler/runtime/ and lang/dist/platform/, not at root.
Setting EL_HOME=$DEST/lang makes RUNTIME_SRC resolve correctly so
build-stage.sh can cp el_runtime.{c,h,js} from the right location.

.gitea/workflows/deploy.yaml

@@ -81,7 +81,7 @@ jobs:
             "https://will:${CHECKOUT_TOKEN}@git.neuralplatform.ai/neuron-technologies/el.git" \
             "$DEST"
           ls -la "$DEST" | head -5
-          echo "EL_HOME=$DEST" >> "$GITHUB_ENV"
+          echo "EL_HOME=$DEST/lang" >> "$GITHUB_ENV"
 
       - name: Authenticate to GCP
         id: auth

.gitea/workflows/stage.yaml

@@ -79,7 +79,7 @@ jobs:
           git clone --depth 1 \
             "https://will:${CHECKOUT_TOKEN}@git.neuralplatform.ai/neuron-technologies/el.git" \
             "$DEST"
-          echo "EL_HOME=$DEST" >> "$GITHUB_ENV"
+          echo "EL_HOME=$DEST/lang" >> "$GITHUB_ENV"
 
       - name: Authenticate to GCP
         uses: google-github-actions/auth@v2