feat(export): v2.1.0 - export multi-formats HTML/MD-bundle/ePub

- backend/export.py: 3 exporters (HTML standalone, ZIP MD, ePub 3)
- HTML: CSS inliné, images base64, navigation wikilinks
- MD bundle: ZIP préserve structure répertoire
- ePub: zipfile + mistune, zero nouvelle dépendance
- 3 endpoints API: /api/export/{html,md-bundle,epub}
- UI: dropdown Export dans toolbar viewer (HTML/MD/ePub)
- 20 tests (validité, contenu, erreurs, API)
- 439 tests passent au total

frontend/js/viewer.js

@@ -1,5 +1,5 @@
 /* ObsiGate — Viewer module */
-import { api } from './auth.js';
+import { api, AuthManager } from './auth.js';
 import { state } from './state.js';
 import { escapeHtml, safeCreateIcons, safeHighlight, getFileIcon, openEditor, copyToClipboard } from './utils.js';
 import { TabManager, closeMobileSidebar, ContextMenuManager, RightSidebarManager, showToast, buildFrontmatterCard } from './ui.js';
@@ -13,6 +13,41 @@ import { openShareDialog } from './config.js';
 import { cacheViewedFile, getCachedFile } from './offline.js';
 import { t } from './i18n.js';
 
+// ── Multi-format export ────────────────────────────────────────────────────
+// Downloads a file export (HTML / MD bundle / ePub) via the authenticated
+// export endpoints, showing a loading toast while the request is in flight.
+async function downloadExport(vault, path, format, fallbackName) {
+  showToast(t("viewer.export_start"), "info");
+  const url = `/api/export/${format}?vault=${encodeURIComponent(vault)}&path=${encodeURIComponent(path)}`;
+  try {
+    const headers = AuthManager.getAuthHeaders() || {};
+    const res = await fetch(url, { credentials: "include", headers });
+    if (!res.ok) {
+      let detail = "";
+      try { detail = (await res.json()).detail || ""; } catch (_) { /* ignore */ }
+      throw new Error(detail || "HTTP " + res.status);
+    }
+    const blob = await res.blob();
+    const a = document.createElement("a");
+    a.href = URL.createObjectURL(blob);
+    a.download = fallbackName;
+    document.body.appendChild(a);
+    a.click();
+    document.body.removeChild(a);
+    setTimeout(() => URL.revokeObjectURL(a.href), 1000);
+    showToast(t("viewer.export_done"), "success");
+  } catch (err) {
+    console.error("Export error:", err);
+    showToast(t("viewer.export_error") + " " + err.message, "error");
+  }
+}
+
+// Close any open export dropdown when clicking elsewhere.
+document.addEventListener("click", function (e) {
+  if (e.target && e.target.closest && e.target.closest(".export-dropdown")) return;
+  document.querySelectorAll(".export-menu").forEach(function (m) { m.style.display = "none"; });
+});
+
 // Pane-aware content area helper — delegates to PaneManager when split
 function getContentArea() {
   // Override set by PaneTabManager._renderFileInPane for cross-module rendering
@@ -635,6 +670,36 @@ export function renderFile(data) {
     window.open(pdfUrl, "_blank");
   });
 
+  // Export dropdown button (HTML / MD bundle / ePub)
+  const exportWrap = el("div", { class: "export-dropdown", style: "position:relative;display:inline-block" });
+  const exportBtn = el("button", { class: "btn-action", title: t("viewer.export_title") }, [icon("download", 14), document.createTextNode(t("viewer.export"))]);
+  const exportMenu = el("div", { class: "export-menu", style: "display:none;position:absolute;right:0;top:100%;z-index:1000;min-width:200px;padding:4px;background:var(--bg,#fff);border:1px solid #ccc;border-radius:6px;box-shadow:0 6px 16px rgba(0,0,0,.18)" });
+  const exportOptions = [
+    { format: "html", icon: "file-code", label: t("viewer.export_html"), ext: ".html" },
+    { format: "md-bundle", icon: "archive", label: t("viewer.export_md_bundle"), ext: ".zip" },
+    { format: "epub", icon: "book-open", label: t("viewer.export_epub"), ext: ".epub" },
+  ];
+  exportOptions.forEach((opt) => {
+    const item = el("button", { class: "export-menu-item", style: "display:flex;align-items:center;gap:8px;width:100%;padding:8px 10px;border:none;background:none;cursor:pointer;border-radius:4px;text-align:left;font-size:13px" }, [
+      icon(opt.icon, 14),
+      document.createTextNode(opt.label),
+    ]);
+    item.addEventListener("mouseenter", () => { item.style.background = "rgba(128,128,128,.15)"; });
+    item.addEventListener("mouseleave", () => { item.style.background = "none"; });
+    item.addEventListener("click", () => {
+      exportMenu.style.display = "none";
+      const baseName = data.path.split("/").pop().replace(/\.[^.]+$/, "") || "document";
+      downloadExport(data.vault, data.path, opt.format, baseName + opt.ext);
+    });
+    exportMenu.appendChild(item);
+  });
+  exportBtn.addEventListener("click", (e) => {
+    e.stopPropagation();
+    exportMenu.style.display = exportMenu.style.display === "block" ? "none" : "block";
+  });
+  exportWrap.appendChild(exportBtn);
+  exportWrap.appendChild(exportMenu);
+
   const editBtn = el("button", { class: "btn-action", title: "Editer" }, [icon("edit", 14), document.createTextNode("Editer")]);
   editBtn.addEventListener("click", () => {
     openEditor(data.vault, data.path);
@@ -754,7 +819,7 @@ export function renderFile(data) {
   // Assemble
   area.innerHTML = "";
   area.appendChild(breadcrumb);
-  area.appendChild(el("div", { class: "file-header" }, [el("div", { class: "file-title" }, [document.createTextNode(data.title)]), tagsDiv, el("div", { class: "file-actions" }, [copyBtn, sourceBtn, mdBtn, pdfBtn, editBtn, forgeBtn, openNewWindowBtn, tocBtn, shareBtn, bookmarkBtn])]));
+  area.appendChild(el("div", { class: "file-header" }, [el("div", { class: "file-title" }, [document.createTextNode(data.title)]), tagsDiv, el("div", { class: "file-actions" }, [copyBtn, sourceBtn, mdBtn, pdfBtn, exportWrap, editBtn, forgeBtn, openNewWindowBtn, tocBtn, shareBtn, bookmarkBtn])]));
   if (fmSection) area.appendChild(fmSection);
   area.appendChild(mdDiv);
   area.appendChild(rawDiv);