Add dark theme support and bookmark status to share view

- Implement dark/light theme toggle with persistent preference via
  localStorage
- Add a sticky toolbar with theme toggle, Markdown export, and PDF
  export buttons
- Update bookmark button to reflect current state with visual feedback
- Introduce CSS custom properties for theming and responsive layout
  improvements

frontend/app.js

@@ -3283,11 +3283,23 @@
     })();
     shareBtn.addEventListener("click", () => openShareDialog(data.vault, data.path));
 
-    // Bookmark button
-    const bookmarkBtn = el("button", { class: "btn-action", title: "Ajouter/Retirer des bookmarks" }, [icon("bookmark-plus", 14), document.createTextNode("Bookmark")]);
+    // Bookmark button — check if already bookmarked
+    const bookmarkBtn = el("button", { class: "btn-action btn-bookmark", title: "Ajouter/Retirer des bookmarks" }, [icon("bookmark-plus", 14), document.createTextNode("Bookmark")]);
+    // Check bookmark status and color the button
+    (async () => {
+      try {
+        const bms = await api("/api/bookmarks");
+        if (Array.isArray(bms) && bms.some(b => b.vault === data.vault && b.path === data.path)) {
+          bookmarkBtn.classList.add("active");
+          bookmarkBtn.title = "Retirer des bookmarks";
+        }
+      } catch (e) { /* ignore */ }
+    })();
     bookmarkBtn.addEventListener("click", async () => {
       try {
         const res = await api("/api/bookmarks/toggle", { method: "POST", headers: { "Content-Type": "application/json" }, body: JSON.stringify({ vault: data.vault, path: data.path, title: data.title }) });
+        bookmarkBtn.classList.toggle("active", res.bookmarked);
+        bookmarkBtn.title = res.bookmarked ? "Retirer des bookmarks" : "Ajouter aux bookmarks";
         showToast(res.bookmarked ? "Ajouté aux bookmarks" : "Retiré des bookmarks", "success");
         if (typeof DashboardBookmarkWidget !== "undefined") DashboardBookmarkWidget.load();
       } catch (err) { showToast("Erreur: " + err.message, "error"); }