feat(privacy+extension): publier la page /privacy et préparer les builds Chrome/Firefox Store

- Nouvelle page /privacy bilingue (FR/EN) avec sélection par Accept-Language
  ou ?lang=, sections complètes (données collectées, IA/BYOK, RGPD, sécurité,
  contact). Style sombre aligné sur la landing (x.ai premium).
- Liens footer landing.footer.legal.* mis à jour vers /privacy dans les 15 locales.
- Extension Web Clipper rendue cross-browser :
  * background.js détecte chrome.sidePanel vs browser.sidebarAction
  * sidepanel.js ajoute un shim chrome<->browser pour Firefox
  * manifest.json inclut sidebar_action + browser_specific_settings.gecko
    + optional_host_permissions (Chrome les ignore)
- Script scripts/build-firefox.mjs pour produire un .xpi signé pour AMO,
  symétrique de build-chrome-store.mjs. Exclusion mutuelle des artefacts
  Chrome/Firefox pour éviter la cross-contamination.
- Branding corrigé : 176 occurrences de 'Momento' -> 'Memento' dans le
  bundle de traductions embarqué.
- Version bumpée 0.3.1 -> 0.4.0.

memento-note/extension/scripts/build-chrome-store.mjs

@@ -40,17 +40,24 @@ function ensureDir(dirPath) {
   }
 }
 
-// Copy all files from source to destination, excluding specified patterns
+// Copy all files from source to destination, excluding specified patterns.
+// `exclude` accepts RegExp (matched against the relative path) or a function
+// returning true when the entry (relative path, isDirectory flag) should be skipped.
 function copyFiles(src, dest, exclude = []) {
   ensureDir(dest)
   const entries = fs.readdirSync(src, { withFileTypes: true })
 
+  const isExcluded = (relPath, isDir) =>
+    exclude.some(rule => {
+      if (typeof rule === 'function') return rule(relPath, isDir)
+      return relPath.match(rule) !== null
+    })
+
   for (const entry of entries) {
     const srcPath = path.join(src, entry.name)
     const relPath = path.relative(extRoot, srcPath)
 
-    // Skip excluded files/directories
-    if (exclude.some(pattern => relPath.match(pattern))) {
+    if (isExcluded(relPath, entry.isDirectory())) {
       continue
     }
 
@@ -85,6 +92,11 @@ function processManifestJson(content) {
     manifest.content_scripts[0].matches = ['https://memento-note.com/*', 'https://www.memento-note.com/*']
   }
 
+  // Strip Firefox-only fields (Chrome Store rejects unknown keys on strict review)
+  delete manifest.sidebar_action
+  delete manifest.browser_specific_settings
+  delete manifest.optional_host_permissions
+
   return JSON.stringify(manifest, null, 2)
 }
 
@@ -177,13 +189,19 @@ async function build() {
     }
     ensureDir(distDir)
 
-    // Copy extension files (excluding build scripts and dist)
+    // Copy extension files (excluding build scripts, internal sources and dist)
     log('📋 Copying extension files...', 'blue')
     copyFiles(extRoot, distDir, [
-      /^dist-/,
-      /^scripts\//,
+      // Top-level directories to skip entirely (do not even create empty folders)
+      (rel, isDir) => isDir && /^dist-/i.test(rel),
+      (rel, isDir) => isDir && (rel === 'scripts' || rel === 'i18n'),
+      // File-level patterns
       /\.md$/,
-      /^node_modules$/
+      /^node_modules$/,
+      /^diagnose\.js$/,           // dev diagnostic script
+      /^test-sidepanel\.html$/,   // dev test page
+      /^memento-web-clipper-chrome-store\.zip$/, // avoid recursive zip-in-zip
+      /^memento-web-clipper-firefox\.xpi$/, // exclude sibling Firefox build artifacts
     ])
 
     // Process sidepanel.js