Address Copilot review: drop dangling nb_repository_url, clear doctrees

- nb_repository_url pointed at lecture-python-programming.fr.notebooks,
  which does not exist; the theme (launch.py) skips notebook-launch
  links entirely when the key is unset, so removing it is clean for an
  HTML-only edition
- publish.yml now clears _build/.doctrees after downloading the cache
  (as ci.yml already did, following lecture-python.myst), removing the
  one staleness vector in the latest-from-main cache convention

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

Author: mmcky

.github/workflows/publish.yml

@@ -49,6 +49,9 @@ jobs:
           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}

lectures/_config.yml

@@ -45,7 +45,8 @@ sphinx:
       header_organisation_url: https://quantecon.org
       header_organisation: QuantEcon
       repository_url: https://github.com/QuantEcon/lecture-python-programming.fr
-      nb_repository_url: https://github.com/QuantEcon/lecture-python-programming.fr.notebooks
+      # nb_repository_url omitted deliberately: no notebooks repo exists for this
+      # edition yet, and the theme skips notebook-launch links when it is unset
       path_to_docs: lectures
       twitter: quantecon
       twitter_logo_url: https://assets.quantecon.org/img/qe-twitter-logo.png