fix: sqlite3.Row .get() → bracket notation in _load_workspace_pages

Same bug as tree API — sqlite3.Row doesn't implement .get(),
only __getitem__ (bracket notation). Fixed icon detection for
folders vs files in sidebar workspace section.

app/routers/board.py

@@ -152,7 +152,7 @@ def _load_workspace_pages(ws_cookie: str) -> list:
                 (ws_id,),
             ).fetchall()
         return [{"db_id": r["id"], "name": r["title"] or "Untitled", "id": f"page/{r['id']}",
-                 "icon": "📁" if r.get("parent_section") == "Workspace" else "📄"} for r in rows]
+                 "icon": "📁" if r["parent_section"] == "Workspace" else "📄"} for r in rows]
     except (ValueError, Exception):
         return []