Implement tasks 1-3: sidebar order, jail activation rollback, pie chart colors

Task 1: Move Configuration to last position in sidebar NAV_ITEMS

Task 2: Add automatic rollback when jail activation fails
- Back up .local override file before writing
- Restore original file (or delete) on reload failure, health-check
  failure, or jail not appearing post-reload
- Return recovered=True/False in JailActivationResponse
- Show warning/critical banner in ActivateJailDialog based on recovery
- Add _restore_local_file_sync and _rollback_activation_async helpers
- Add 3 new tests: rollback on reload failure, health-check failure,
  and double failure (recovered=False)

Task 3: Color pie chart legend labels to match their slice color
- legendFormatter now returns ReactNode with span style={{ color }}
- Import LegendPayload from recharts/types/component/DefaultLegendContent

frontend/src/components/TopCountriesPieChart.tsx

@@ -12,6 +12,7 @@ import {
   Tooltip,
 } from "recharts";
 import type { PieLabelRenderProps } from "recharts";
+import type { LegendPayload } from "recharts/types/component/DefaultLegendContent";
 import type { TooltipContentProps } from "recharts/types/component/Tooltip";
 import { tokens, makeStyles, Text } from "@fluentui/react-components";
 import { CHART_PALETTE, resolveFluentToken } from "../utils/chartTheme";
@@ -153,12 +154,19 @@ export function TopCountriesPieChart({
     );
   }
 
-  /** Format legend entries as "Country Name (xx%)" */
-  const legendFormatter = (value: string): string => {
+  /** Format legend entries as "Country Name (xx%)" and colour them to match their slice. */
+  const legendFormatter = (
+    value: string,
+    entry: LegendPayload,
+  ): React.ReactNode => {
     const slice = slices.find((s) => s.name === value);
     if (slice == null || total === 0) return value;
     const pct = ((slice.value / total) * 100).toFixed(1);
-    return `${value} (${pct}%)`;
+    return (
+      <span style={{ color: entry.color }}>
+        {value} ({pct}%)
+      </span>
+    );
   };
 
   return (