feat: SEO improvements — related content, IndexNow, manifest, llms.txt

- Enable showRelatedContent + showSummary in article config
- Add IndexNow ping step to CI deploy pipeline
- Fix site.webmanifest branding (was Congo, now Internet for Kids)
- Update llms.txt to include French language section

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/deploy.yml

@@ -163,6 +163,24 @@ jobs:
           fi
           echo "All smoke tests passed"
 
+  indexnow:
+    name: IndexNow Ping
+    runs-on: ubuntu-latest
+    needs: [smoke-test]
+    steps:
+      - name: Notify search engines
+        run: |
+          KEY="40101d97ec848f6ea016fac347b1a5bc"
+          for url in \
+            "https://internetforkids.org/" \
+            "https://internetforkids.org/en/" \
+            "https://internetforkids.org/de/" \
+            "https://internetforkids.org/fr/" \
+            "https://internetforkids.org/sitemap.xml"; do
+            curl -sf "https://api.indexnow.org/indexnow?url=${url}&key=${KEY}" || true
+          done
+          echo "IndexNow pings sent"
+
   promote:
     name: Promote to Latest
     runs-on: ubuntu-latest