ci: add GitHub Actions workflow for documentation build and deploy

.github/workflows/docs.yml

@@ -0,0 +1,88 @@
+# Build and deploy documentation using Sphinx
+#
+# On pull requests: builds docs to verify they compile without errors.
+# On pushes to main: builds and deploys to GitHub Pages.
+#
+# This workflow is documentation-tooling agnostic — it runs whichever
+# Sphinx build is configured in docs/conf.py. If the project switches
+# to Jupyter Book or another Sphinx-based tool, only the install step
+# and build command need updating.
+name: Documentation
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - "docs/**"
+      - "neural_lam/**"
+      - ".github/workflows/docs.yml"
+  pull_request:
+    branches: [main]
+    paths:
+      - "docs/**"
+      - "neural_lam/**"
+      - ".github/workflows/docs.yml"
+
+# Allow only one concurrent deployment
+concurrency:
+  group: "pages"
+  cancel-in-progress: false
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python 3.12
+        uses: actions/setup-python@v6
+        with:
+          python-version: "3.12"
+
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y graphviz
+
+      - name: Install neural-lam and doc dependencies
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install -e .
+          python -m pip install -r docs/requirements.txt
+
+      - name: Build documentation
+        working-directory: docs
+        run: |
+          sphinx-build -b html . _build/html -W --keep-going -n
+        env:
+          MPLBACKEND: Agg
+
+      - name: Check for broken links
+        working-directory: docs
+        continue-on-error: true
+        run: |
+          sphinx-build -b linkcheck . _build/linkcheck
+
+      - name: Upload documentation artifact
+        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: docs/_build/html
+
+  deploy:
+    needs: build
+    if: github.event_name == 'push' && github.ref == 'refs/heads/main'
+    runs-on: ubuntu-latest
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4

docs/requirements.txt

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+# Documentation build dependencies
+# Install with: pip install -r docs/requirements.txt
+sphinx>=7.0
+pydata-sphinx-theme>=0.15
+sphinx-autoapi>=3.0
+numpydoc>=1.6
+sphinx-copybutton>=0.5