chore: import upstream snapshot with attribution

.github/workflows/publish.yaml

@@ -0,0 +1,80 @@
+name: Publish
+
+on:
+  workflow_dispatch:
+    inputs:
+      use_testpypi:
+        description: 'Publish to TestPyPI instead of PyPI'
+        required: false
+        default: false
+        type: boolean
+  release:
+    types: [published]
+
+permissions: read-all
+
+jobs:
+  validate:
+    name: Validate inputs
+    runs-on: ubuntu-slim
+    steps:
+      - name: Validate publishing branch and destination package index
+        run: |
+          if [[ "${{ github.ref_name }}" != "main" && "${{ github.event_name }}" != "release" ]]; then
+            if [[ "${{ inputs.use_testpypi }}" != "true" ]]; then
+              echo "❌ Error: Only build from main branch or release tag can be published to PyPI."
+              echo "Please check 'Publish to TestPyPI instead of PyPI' when running from branch: ${{ github.ref_name }}"
+              exit 1
+            fi
+          fi
+          echo "✅ Validation passed"
+  ci:
+    needs: [validate]
+    uses: ./.github/workflows/ci.yaml
+    secrets: inherit
+  build-n-publish:
+    name: Upload release to PyPI/TestPyPI
+    runs-on: ubuntu-latest
+    needs: [ci]
+    env:
+      name: ${{ inputs.use_testpypi && 'testpypi' || 'pypi' }}
+      url: ${{ inputs.use_testpypi && 'https://test.pypi.org/project/chainlit' || 'https://pypi.org/project/chainlit' }}
+      BACKEND_DIR: ./backend
+    permissions:
+      contents: read
+      id-token: write # IMPORTANT: this permission is mandatory for trusted publishing
+    steps:
+      - uses: actions/checkout@v6
+      - uses: ./.github/actions/pnpm-node-install
+        name: Install Node, pnpm and dependencies.
+      - uses: ./.github/actions/uv-python-install
+        name: Install Python, uv and Python dependencies
+        with:
+          working-directory: ${{ env.BACKEND_DIR }}
+
+      - name: Build Python distribution
+        run: uv build
+        working-directory: ${{ env.BACKEND_DIR }}
+
+      - name: Check frontend and copilot folder included
+        run: |
+          pip install wheel
+          python -m wheel unpack dist/chainlit-*.whl -d unpacked
+          ls unpacked/chainlit-*/chainlit/frontend/dist
+          ls unpacked/chainlit-*/chainlit/copilot/dist
+
+      - name: Publish package distributions to TestPyPI
+        if: inputs.use_testpypi
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          packages-dir: dist
+          repository-url: https://test.pypi.org/legacy/
+          password: ${{ secrets.TEST_PYPI_API_TOKEN }}
+          verbose: true
+
+      - name: Publish package distributions to PyPI
+        if: ${{ !inputs.use_testpypi }}
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          packages-dir: dist
+          password: ${{ secrets.PYPI_API_TOKEN }}