Add French translation sync workflow (sync-translations-fr.yml) (#573)

* Add French translation sync workflow (sync-translations-fr.yml)

Clone of sync-translations-fa.yml with target-repo
QuantEcon/lecture-python-programming.fr, target-language fr, pinned at
action-translation@v0.15.0. Do not merge until the fr bulk bootstrap
(translate init) has landed in the target repo.

Part of the fr rollout tracked in QuantEcon/project-translation#3

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

* Pin French sync to action-translation v0.16.0

This PR predated the v0.16.0 release, so it pinned v0.15.0 (default model
claude-sonnet-4-6). v0.16.0 defaults to claude-sonnet-5, which is the point of
pointing French at it.

Diverges deliberately from the fa and zh-cn sync workflows, which stay on
v0.15.0/Sonnet 4.6: French is the edition evaluated on Sonnet 5, and silently
changing the model for two established editions is not this PR's business.

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: mmcky

.github/workflows/sync-translations-fr.yml

@@ -0,0 +1,35 @@
+# Sync Translations — French
+# On merged PR, translate changed lectures into the French target repo.
+# Comment \translate-resync on a merged PR to re-trigger sync.
+name: Sync Translations (French)
+
+on:
+  pull_request:
+    types: [closed]
+    paths:
+      - 'lectures/**/*.md'
+      - 'lectures/_toc.yml'
+  issue_comment:
+    types: [created]
+
+jobs:
+  sync:
+    if: >
+      (github.event_name == 'pull_request' && github.event.pull_request.merged == true) ||
+      (github.event_name == 'issue_comment' && contains(github.event.comment.body, '\translate-resync'))
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          fetch-depth: 2
+
+      - uses: QuantEcon/action-translation@v0.16.0
+        with:
+          mode: sync
+          target-repo: QuantEcon/lecture-python-programming.fr
+          target-language: fr
+          source-language: en
+          docs-folder: lectures
+          anthropic-api-key: ${{ secrets.ANTHROPIC_API_KEY }}
+          github-token: ${{ secrets.QUANTECON_SERVICES_PAT }}