feat: Order Queue Time Report — real-time management dashboard

[Copilot]

Adds a management dashboard for real-time order queue monitoring, prep time analytics, peak hour identification, and CSV report exports.

Backend

• Order model — added OrderStatus (Pending/InProgress/Completed/Cancelled), OrderType (Pickup/Delivery), StartedAt, CompletedAt timestamps
• OrderQueueService — new service providing: live queue stats with elapsed times, average prep time (last 24h, optionally filtered by order type), per-hour peak analysis, daily historical metrics, and UTF-8 CSV export
• QueueController — new endpoints:
  • GET /api/queue/stats — active orders + KPIs
  • GET /api/queue/average-prep-time?orderType= — 24h average
  • GET /api/queue/peak-hours?days= — hourly order volume + avg wait
  • GET /api/queue/history?days= — daily aggregates
  • GET /api/queue/export/csv?days= — file download
• OrdersController — added PATCH /api/orders/{id}/status with auto-timestamping of StartedAt/CompletedAt
• Program.cs — registers OrderQueueService, enables StringEnumConverter, seeds ~84 demo orders spanning 14 days for dashboard testing

Frontend

• ManagementDashboard — new /management page with:
  • KPI cards: queue depth, avg prep time, estimated wait for next order, today's revenue
  • Live order queue table with inline Start / Complete / Cancel actions
  • Peak hours bar chart (9 AM–9 PM, configurable day range)
  • Historical performance table (total orders, completed, avg prep, revenue per day)
  • CSV export with configurable date range (7/30/90 days)
  • Auto-refreshes every 30 s; all heavy memoized appropriately
• Header — added "📊 Management" nav link
• types/index.ts — OrderStatus, OrderType, QueueStats, ActiveOrderInfo, PeakHourData, DailyMetrics
• api.ts — queue API functions + browser-side CSV download trigger

Original prompt

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This section details on the original issue you should resolve

<issue_title>Order Queue Time Report</issue_title>
<issue_description>Real-time order queue monitoring and analytics dashboard for store management to track preparation times and optimize operations.

Features:

• Real-time queue visualization with current orders
• Average preparation time per order type (pickup/delivery)
• Peak hours analysis with order volume trends
• Customer wait time estimation
• Historical performance metrics
• CSV export for reports

Technical Requirements:

• Backend: OrderQueueService for timing metrics
• Frontend: Management dashboard page
• Database: Order timestamps (created, started, completed)
• API: Queue stats and historical data endpoints
• Real-time updates via SignalR or polling

Acceptance Criteria:

• Dashboard displays current orders with elapsed time
• Shows average prep time (last 24 hours)
• Visual peak hour identification
• Estimated wait time for new orders
• Daily/weekly/monthly report exports
• Mobile responsive for tablet access
• Role-based access (managers only)</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Order Queue Time Report #28

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