Fix Frontend Workbench Display

Goal

Make the authenticated workbench reflect real application data and simplify the navigation-heavy UI so it does not duplicate the sidebar.

The user reported that the frontend workbench data does not match actual data.
The current dashboard.jsp hard-codes metric values, popular book ranking rows, borrowing rows, overdue rows, and book rows.
The workbench shortcut cards for 读者管理, 报表中心, 借阅流通, and 系统日志 duplicate links already present in the sidebar.
The UI uses circular single-character markers beside text in metrics, shortcut cards, sidebar links, role chips, and topbar user summary.
The sidebar is fixed on desktop, but responsive CSS changes .app-sidebar and .app-topbar to static layout under 960px, effectively removing the persistent sidebar behavior.
Existing report infrastructure already exposes actual inventory summary, borrowing summary, overdue rows, and popular books through ReportService.loadReportCenter(...).

"UI text beside an unnecessary circle with one character" applies to decorative single-character icon circles in the authenticated shell and workbench, not to plain text labels or table status pills.
The workbench should reuse existing server-rendered JSP/Servlet patterns rather than introducing client-side state.
When a specific real data source does not yet exist, prefer showing an existing real metric over keeping a static fake metric.

Replace hard-coded workbench summary metrics with real data.
Replace the hard-coded popular book ranking with real ranking data.
Replace hard-coded borrowing/overdue/book table samples with real data or remove the fake sample rows in favor of empty states.
Keep the workbench catalog search category selector populated from real categories.
Remove the workbench shortcut entry block containing 读者管理, 报表中心, 借阅流通, and 系统日志.
Remove the decorative circular single-character UI markers around text in the authenticated shell/workbench where they are not functionally necessary.
Ensure the sidebar cannot be hidden or collapsed by responsive layout rules.
Keep role-based visibility and permissions intact for administrator, librarian, and reader users.

Workbench metrics are rendered from request attributes populated by backend services, not hard-coded numbers.
Popular ranking and table content no longer contain static sample records such as 张晓明, 活着, 三体, or fixed 2024 dates unless those values come from the database.
The workbench no longer shows shortcut cards for 读者管理, 报表中心, 借阅流通, or 系统日志.
Decorative single-character circles next to UI text are removed or restyled as plain text/spacing without circular badges.
Sidebar remains visible and occupies its sidebar column across responsive breakpoints.
Existing navigation links still work and remain role-aware.
Project lint/type-check or the closest available Java build/test command passes.

Adding new major dashboard modules beyond the current workbench content.
Redesigning unrelated pages outside the shared authenticated shell and workbench.
Changing database schema unless necessary to replace static workbench data.

Likely files: src/main/java/com/mzh/library/controller/DashboardServlet.java, src/main/webapp/WEB-INF/jsp/dashboard.jsp, src/main/webapp/WEB-INF/jsp/common/header.jspf, and src/main/webapp/static/css/app.css.
Existing actual report data: ReportServiceImpl, JdbcReportDao, ReportCenter, InventorySummary, BorrowingSummary, OverdueReportRow, and PopularBookReportRow.
Existing category/book patterns: BookServiceImpl, JdbcBookDao, and BookCatalogServlet.
Existing borrowing list pattern: BorrowingServiceImpl.searchRecords(...) and BorrowingManagementServlet.