feat(tools): count and summarize every match in the area tools

aircraft_in_area and vessels_in_area return at most 200 rows, so a client
asked which operators dominate an area, or the average altitude there, could
only estimate from a truncated sample. Both tools now take an optional
group_by (aircraft: operator, origin_country, type_code; ships: type,
destination) and stats (airborne altitude and speed for aircraft, speed for
ships). Each is computed over every match before rows are capped. Breakdowns
list the ten largest groups plus other and unknown counts, and the summary
names the three largest.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/tools/results.js

@@ -22,6 +22,75 @@ export function capRows(rows, limit = DEFAULT_LIMIT) {
   };
 }
 
+/** Most groups a breakdown lists before counting the rest as other. */
+export const MAX_GROUPS = 10;
+
+/**
+ * Count rows by one text field over every row, not just those returned.
+ * Values group case-insensitively and keep their first spelling; rows
+ * without a value are counted as unknown.
+ */
+export function breakdown(rows, field) {
+  const groups = new Map();
+  let unknown = 0;
+  for (const row of rows) {
+    const value = typeof row[field] === 'string' ? row[field].trim() : '';
+    if (!value) {
+      unknown += 1;
+      continue;
+    }
+    const key = value.toLowerCase();
+    const group = groups.get(key);
+    if (group) group.count += 1;
+    else groups.set(key, { value, count: 1 });
+  }
+  const sorted = [...groups.values()].sort(
+    (a, b) => b.count - a.count || a.value.localeCompare(b.value),
+  );
+  const listed = sorted.slice(0, MAX_GROUPS);
+  return {
+    field,
+    groups: listed,
+    other_count: rows.length - unknown - sum(listed.map((g) => g.count)),
+    unknown_count: unknown,
+  };
+}
+
+/** Minimum, median, mean and maximum of one numeric field, or null. */
+export function numericSummary(rows, field) {
+  const values = rows
+    .map((row) => row[field])
+    .filter(Number.isFinite)
+    .sort((a, b) => a - b);
+  if (!values.length) return null;
+  const middle = values.length >> 1;
+  const median =
+    values.length % 2
+      ? values[middle]
+      : (values[middle - 1] + values[middle]) / 2;
+  const round1 = (value) => Number(value.toFixed(1));
+  return {
+    count: values.length,
+    min: values[0],
+    median: round1(median),
+    mean: round1(sum(values) / values.length),
+    max: values.at(-1),
+  };
+}
+
+/** "; most by operator: Delta (12), United (9), American (7)" or "". */
+export function breakdownPhrase(result, label) {
+  if (!result.groups.length) return '';
+  const top = result.groups
+    .slice(0, 3)
+    .map((group) => `${group.value} (${group.count})`);
+  return `; most by ${label}: ${top.join(', ')}`;
+}
+
+function sum(values) {
+  return values.reduce((total, value) => total + value, 0);
+}
+
 /** Format an epoch millisecond time as ISO 8601, or null. */
 export function isoTime(ms) {
   return Number.isFinite(ms) ? new Date(ms).toISOString() : null;