Remove all Node.js actions, use pure shell for CI/CD

The act runner has no Node.js in container jobs. Replace
actions/upload-artifact and actions/download-artifact with
direct Gitea API uploads from a single job that builds all
three architectures sequentially.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -12,29 +12,16 @@ jobs:
     container:
       image: rust:1.86-slim
     steps:
-      - name: Debug workspace
-        run: |
-          echo "PWD: $(pwd)"
-          echo "HOME: $HOME"
-          echo "GITHUB_WORKSPACE: ${GITHUB_WORKSPACE:-unset}"
-          ls -la .
-          ls -la .. || true
-          find / -name "Cargo.toml" 2>/dev/null | head -5 || true
-
       - name: Install git
         run: apt-get update && apt-get install -y --no-install-recommends git
 
-      - name: Checkout code
+      - name: Ensure code is present
         run: |
           git config --global --add safe.directory '*'
-          if [ -f "Cargo.toml" ]; then
-            echo "Code already in workspace"
-          else
-            echo "Cloning repo..."
+          if [ ! -f "Cargo.toml" ]; then
             git clone --depth 1 ${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY}.git /tmp/src
             cp -a /tmp/src/. .
           fi
-          ls -la Cargo.toml
 
       - name: Run tests
         run: cargo test -- --test-threads=1