Rebuild du site sur Astro : i18n multilingue, faits verifies, Docker, CI, tests

- Astro statique, EN par defaut + /fr/ + /nl/, detection langue navigateur
- i18n par fichiers JSON, ajouter une langue = ajouter des traductions
- Contenu original porte a l'identique (diff d'inventaire par langue)
- Chronologie legislative corrigee sur sources primaires (PE, Conseil, votes)
- Timeline 23 precedents + observatoire 35 items + annuaire 66 outils FOSS,
  chaque affirmation verifiee et sourcee
- Zero requete tierce (teste), lisible JS coupe, axe WCAG AA x2 themes
- Version offline monofichier par langue a chaque build
- Docker multi-stage vers nginx + CSP stricte auto-generee
- CI GitHub Actions (SHA-pinnees) + verification hebdo des liens
- CONTRIBUTING : divulgation d'affiliation obligatoire, allowlist de
  domaines testee en CI

docker/csp.conf

@@ -0,0 +1 @@
+add_header Content-Security-Policy "default-src 'none'; script-src 'self' 'sha256-APKfv1xaOELs5yz+tPQqjel8CVdobT1z0n9rysaGXPk=' 'sha256-FaYmk1uHh+UNUdWrZIkUBDinPxk/ARkHrA23xUfa/Gk=' 'sha256-8UX5i4mkZDhNhuSxNOdkip2H+FxRXqR708bF3BQPnko=' 'sha256-KU52uW0NoYJbkMOy2EcHza0G3yVB1nScn+wH44Buzr4=' 'sha256-4h+PBVSAvnFY4ecAonGUp9Ne4aHhAuAU8je+PqVl6I4=' 'sha256-J7fub090nAsxTSG8BOZrqblL942lG2lnHuFfzZkky7o=' 'sha256-4hyaOQzqvLr9R6SuXkYh80AxSXJ0K9kC9zbii9v8DGY='; style-src 'self'; img-src 'self' data:; font-src 'self'; manifest-src 'self'; base-uri 'none'; form-action 'none'; frame-ancestors 'none'" always;

docker/nginx.conf

@@ -0,0 +1,27 @@
+server {
+    listen 8080;
+    listen [::]:8080;
+    server_name _;
+
+    root /usr/share/nginx/html;
+    index index.html;
+    charset utf-8;
+
+    gzip_static on;
+
+    error_page 404 /404.html;
+
+    # hashed build assets: cache forever
+    location /_astro/ {
+        include /etc/nginx/snippets/security-headers.conf;
+        add_header Cache-Control "public, max-age=31536000, immutable" always;
+        try_files $uri =404;
+    }
+
+    # everything else (HTML, sitemap, offline artifact): revalidate
+    location / {
+        include /etc/nginx/snippets/security-headers.conf;
+        add_header Cache-Control "no-cache" always;
+        try_files $uri $uri/ =404;
+    }
+}

docker/security-headers.conf

@@ -0,0 +1,10 @@
+# Shared security headers. nginx's add_header does NOT inherit across
+# levels once a location adds its own header, so every location includes
+# this snippet explicitly.
+include /etc/nginx/snippets/csp.conf;
+add_header X-Content-Type-Options "nosniff" always;
+add_header X-Frame-Options "DENY" always;
+add_header Referrer-Policy "no-referrer" always;
+add_header Permissions-Policy "camera=(), microphone=(), geolocation=(), interest-cohort=()" always;
+add_header Cross-Origin-Opener-Policy "same-origin" always;
+add_header Cross-Origin-Resource-Policy "same-origin" always;