fix: Library button preserves workspace context

3 bugs fixed:
1. dashboard.py /library was registered before board.router and had no workspace context → removed old endpoint, re-added with owner/repo params using board._sidebar_data()
2. base.html navigateTo('/library') lost workspace → now auto-appends ?owner=X&repo=Y from workspaceKey
3. openLibrary(id) used bare window.location.href → now uses this.navigateTo()

Now the Library page:
- Shows pages filtered by workspace when coming from a project
- Preserves the sidebar context (no more Admin Dashboard fallback)
- Tabs (Recents, Favorites, Shared, Private) display project pages from DB

app/templates/base.html

@@ -455,6 +455,11 @@
       },
 
       navigateTo(url) {
+        // Preserve workspace context when navigating to library/trash
+        if ((url === '/library' || url === '/trash') && this.workspaceKey && this.workspaceKey.includes('/')) {
+          const parts = this.workspaceKey.split('/');
+          url = `${url}?owner=${parts[0]}&repo=${parts.slice(1).join('/')}`;
+        }
         window.location.href = url;
       },
 
@@ -538,7 +543,7 @@
       },
 
       openLibrary(id) {
-        window.location.href = '/library';
+        this.navigateTo('/library');
       },
       openInLibrary(id) { this.openLibrary(id); },
       showMore(id) { console.log('Show more:', id); },