Add Netlify PR previews (ci.yml) for reviewer-facing rendered builds

Uses quantecon/actions/preview-netlify@v0.8.0 (the lecture-python.myst
pattern), HTML only, on ubuntu-latest. The action posts a PR comment
with the preview URL and the changed lectures, so translation review
can happen on rendered French pages rather than MyST diffs.

Requires two secrets not yet available to this repo: the org-level
NETLIFY_AUTH_TOKEN extended to include this repo, and a repo-level
NETLIFY_SITE_ID for a new Netlify site. Until they exist the preview
step self-skips for untrusted actors but will fail for in-repo PRs, so
grant them before merging or expect red previews.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: mmcky

.github/workflows/ci.yml

@@ -0,0 +1,62 @@
+name: Build Project [using jupyter-book]
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+jobs:
+  preview:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: write
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+          fetch-depth: 0
+      - name: Setup Anaconda
+        uses: conda-incubator/setup-miniconda@v4
+        with:
+          auto-update-conda: true
+          auto-activate-base: true
+          miniconda-version: 'latest'
+          python-version: "3.13"
+          environment-file: environment.yml
+          activate-environment: quantecon
+      - name: Display Conda Environment Versions
+        shell: bash -l {0}
+        run: conda list
+      - name: Display Pip Versions
+        shell: bash -l {0}
+        run: pip list
+      - name: Download "build" folder (cache)
+        uses: dawidd6/action-download-artifact@v21
+        with:
+          workflow: cache.yml
+          branch: main
+          name: build-cache
+          path: _build
+      - name: Clear stale Sphinx environment
+        shell: bash -l {0}
+        run: rm -rf _build/.doctrees
+      # HTML only for now — no PDF or notebook assets
+      - name: Build HTML
+        shell: bash -l {0}
+        run: |
+          jb build lectures --path-output ./ -n --keep-going
+          # TODO: Re-enable -W flag once all lectures are translated and warnings are resolved
+      - name: Upload Execution Reports
+        uses: actions/upload-artifact@v7
+        if: failure()
+        with:
+          name: execution-reports
+          path: _build/html/reports
+      - name: Setup Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version: '20'
+      - name: Preview Deploy to Netlify
+        uses: quantecon/actions/preview-netlify@v0.8.0
+        with:
+          netlify-auth-token: ${{ secrets.NETLIFY_AUTH_TOKEN }}
+          netlify-site-id: ${{ secrets.NETLIFY_SITE_ID }}
+          build-dir: _build/html