feat(dashboard): implement number formatting for country distribution and notice types

- Integrated formatShortNumber utility to display formatted numbers in the CountryDistribution and NoticeTypeBreakdown components.
- Enhanced user experience by providing clearer visual representation of numerical data with optional positive prefixes.

src/lib/format-number.ts

@@ -1,10 +1,56 @@
-export function compactFormat(value: number) {
-  const formatter = new Intl.NumberFormat("en", {
-    notation: "compact",
-    compactDisplay: "short",
-  });
+export type FormatShortNumberOptions = {
+  /** Prefix positive values with "+" (e.g. +37k) */
+  plus?: boolean;
+  /** Fraction digits for K / M / B suffixes (default 1) */
+  maximumFractionDigits?: number;
+};
 
-  return formatter.format(value);
+function trimTrailingZeros(value: string) {
+  return value.replace(/\.0+$/, "").replace(/(\.[0-9]*?)0+$/, "$1");
+}
+
+function formatScaled(value: number, maximumFractionDigits: number) {
+  if (Number.isInteger(value)) return String(value);
+  return trimTrailingZeros(value.toFixed(maximumFractionDigits));
+}
+
+/**
+ * Shortens large numbers for display: 37030 → "37k", 2500000 → "2.5M".
+ * Use `plus: true` for "+37k" style labels (e.g. chart totals).
+ */
+export function formatShortNumber(
+  value: number,
+  options?: FormatShortNumberOptions,
+): string {
+  const { plus = false, maximumFractionDigits = 1 } = options ?? {};
+
+  if (!Number.isFinite(value)) return "—";
+
+  const sign =
+    value < 0 ? "-" : plus && value > 0 ? "+" : "";
+  const abs = Math.abs(value);
+
+  let body: string;
+
+  if (abs < 1000) {
+    body =
+      abs % 1 === 0
+        ? String(Math.round(abs))
+        : trimTrailingZeros(abs.toFixed(maximumFractionDigits));
+  } else if (abs < 1_000_000) {
+    body = `${formatScaled(abs / 1000, maximumFractionDigits)}k`;
+  } else if (abs < 1_000_000_000) {
+    body = `${formatScaled(abs / 1_000_000, maximumFractionDigits)}M`;
+  } else {
+    body = `${formatScaled(abs / 1_000_000_000, maximumFractionDigits)}B`;
+  }
+
+  return `${sign}${body}`;
+}
+
+/** @deprecated Prefer `formatShortNumber` — kept for existing imports */
+export function compactFormat(value: number) {
+  return formatShortNumber(value);
 }
 
 export function standardFormat(value: number) {
@@ -12,4 +58,4 @@ export function standardFormat(value: number) {
     minimumFractionDigits: 2,
     maximumFractionDigits: 2,
   });
-}
+}