fix: PDF viewer — URL encode filename + error fallback

- dashboard.py: quote(filename) dans file_url (espaces/caractères spéciaux)
- page_editor.html: iframe PDF → onerror fallback avec lien Open in new tab
- 143 tests passent

app/routers/dashboard.py

@@ -325,7 +325,9 @@ async def view_page_root(request: Request, page_id: int):
                 ws_id = p.replace("workspace_", "")
                 break
         filename = fp_parts[-1] if fp_parts else page.get("title", "File")
-        file_url = f"/api/files/{ws_id}/{filename}" if ws_id else ""
+        from urllib.parse import quote
+        safe_name = quote(filename, safe='')
+        file_url = f"/api/files/{ws_id}/{safe_name}" if ws_id else ""
         page_data["file_url"] = file_url
         page_data["file_mime"] = mime_type
         page_data["file_size"] = file_size

app/templates/page_editor.html

@@ -575,7 +575,7 @@ page_title %}{{ page.title }}{% endblock %} {% block topbar %}
       if(b.type==='divider')return `<div class="block-wrapper"><hr class="block-divider"></div>`;
       if(b.type==='image')return `<div class="block-wrapper"><div class="block-content block-image" style="text-align:center;padding:12px 0;"><img src="${b.src||''}" alt="${esc(b.alt||'')}" style="max-width:100%;max-height:70vh;border-radius:8px;display:block;margin:0 auto;" onerror="this.style.display='none';this.parentElement.innerHTML='<div style=\\'padding:40px;color:var(--text-tertiary)\\'>Image not found</div>'"></div></div>`;
       if(b.type==='embed'){
-        if(b.embed_type==='pdf')return `<div class="block-wrapper"><div class="block-content block-embed" style="padding:0;"><iframe src="${b.src||''}" style="width:100%;height:80vh;border:none;border-radius:8px;"></iframe></div></div>`;
+        if(b.embed_type==='pdf')return `<div class="block-wrapper"><div class="block-content block-embed" style="padding:0;"><iframe src="${b.src||''}" style="width:100%;height:80vh;border:none;border-radius:8px;" onerror="this.style.display='none';this.nextElementSibling.style.display='block';"></iframe><div style="display:none;text-align:center;padding:32px;color:var(--text-secondary);"><svg width="48" height="48" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5"><path d="M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z"/><polyline points="14 2 14 8 20 8"/></svg><p style="margin-top:8px;">Failed to load PDF</p><a href="${b.src||''}" target="_blank" style="color:var(--accent);">Open in new tab →</a></div></div></div>`;
         if(b.embed_type==='download'){
           var sz=b.file_size||0;var szStr=sz<1024?sz+' B':sz<1048576?(sz/1024).toFixed(1)+' KB':(sz/1048576).toFixed(1)+' MB';
           return `<div class="block-wrapper"><div class="block-content block-embed" style="text-align:center;padding:60px 20px;"><div style="font-size:48px;margin-bottom:12px;">{{ fd_icon("paperclip",14) }}</div><div style="font-size:16px;font-weight:500;color:var(--text-primary);margin-bottom:4px;">${esc(b.file_name||'File')}</div><div style="font-size:12px;color:var(--text-tertiary);margin-bottom:16px;">${szStr} · ${esc(b.file_mime||'')}</div><a href="${b.src||''}" download style="display:inline-block;padding:8px 20px;background:var(--accent);color:#fff;text-decoration:none;border-radius:8px;font-size:13px;font-weight:500;">⬇ Download</a></div></div>`;