feat(dashboard): add revenue target and cost per route widgets

[Caneryy]

Summary

Resolves two open dashboard issues:

Closes #415
Closes #416

Changes

#415 — Cost per Route Analytics Widget

• Created CostPerRouteWidget.tsx with horizontal stacked bar chart for top 10 routes by cost
• Segmented bars by cost components: base, fuel, customs, insurance
• Added chart/table view toggle with margin color-coding (green > 20%, yellow 10–20%, red < 10%)
• Clicking a route opens a drill-down modal listing shipments on that route
• Tooltip shows per-segment cost breakdown

#416 — Monthly Revenue vs Target Gauge Widget

• Created RevenueTargetWidget.tsx with Recharts RadialBarChart gauge
• Center text shows current revenue and % of target achieved
• Gauge fill color by threshold: green ≥ 100%, blue 75–99%, orange 50–74%, red < 50%
• Displays actual vs target values and projected end-of-month revenue from daily run rate
• Added daily revenue sparkline for the current month

Integration

• Added both widgets to CompanyDashboard.tsx below RevenueSummaryWidget
• Exported widgets from components/index.ts

Test plan

• Unit tests for gauge thresholds, margin calculations, widget rendering, table toggle, and route drill-down modal
• Open company dashboard and verify both widgets render side by side
• Confirm gauge color and center text update with achievement ratio
• Toggle Cost per Route chart/table views and open route modal from both views