feat(flight-live): follow booked flights live from keyless ADS-B feeds

A new flight-live domain polls the open feeds adsb.lol and adsb.fi (no key,
no cost; adsb.fi only on self-hosted installs, its terms are non-commercial)
for every booked flight leg in its watch window, derives phase, take-off,
landing, delay and an arrival estimate, and pushes changes as flight:live.
GET /api/trips/:tripId/flights/live, the MCP tool get_trip_flight_status,
notifications for take-off, landing and delays, and the admin switch
flight_live_enabled (FLIGHT_LIVE_ENABLED wins) come with it.

server/scripts/build-airlines.mjs

@@ -0,0 +1,115 @@
+#!/usr/bin/env node
+// Build server/assets/airlines-icao.json, the IATA airline code -> ICAO callsign prefix table the
+// live flight status uses to turn a booked flight number ("LH 716") into the callsign an aircraft
+// transmits ("DLH716").
+//
+// Source: VRS standing data (github.com/vradarserver/standing-data, CC0): airlines/schema-01 for
+// the codes and the file list of routes/schema-01 for which airline still flies.
+//
+// Only airlines with both codes are kept. IATA reuses its two-character codes, so one IATA code
+// often names several ICAO airlines (LH: Lufthansa and Lufthansa Cargo; U2: easyJet and United
+// Feeder Service). The airline list carries no "active" flag, so the rule is: the ICAO airline
+// with the most route data in the standing data wins (the summed size of its routes files), since
+// routes are only recorded for callsigns seen flying. A shared code where no candidate has any
+// route data is left out rather than guessed; a booking with it is then simply not tracked.
+import fs from 'node:fs';
+import https from 'node:https';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const OUT = path.join(__dirname, '..', 'assets', 'airlines-icao.json');
+const AIRLINES = 'https://raw.githubusercontent.com/vradarserver/standing-data/main/airlines/schema-01/airlines.csv';
+const TREE = 'https://api.github.com/repos/vradarserver/standing-data/git/trees/main?recursive=1';
+
+function fetchText(url) {
+  return new Promise((resolve, reject) => {
+    https
+      .get(url, { headers: { 'User-Agent': 'trek-build-airlines', Accept: '*/*' } }, (res) => {
+        if (res.statusCode !== 200) return reject(new Error(`HTTP ${res.statusCode} for ${url}`));
+        let data = '';
+        res.setEncoding('utf8');
+        res.on('data', (chunk) => {
+          data += chunk;
+        });
+        res.on('end', () => resolve(data));
+      })
+      .on('error', reject);
+  });
+}
+
+/** One CSV line into its fields: optional double quotes, "" as an escaped quote. */
+function parseLine(line) {
+  const fields = [];
+  let cur = '';
+  let inQuotes = false;
+  for (let i = 0; i < line.length; i++) {
+    const ch = line[i];
+    if (inQuotes) {
+      if (ch === '"' && line[i + 1] === '"') {
+        cur += '"';
+        i++;
+      } else if (ch === '"') inQuotes = false;
+      else cur += ch;
+    } else if (ch === '"') inQuotes = true;
+    else if (ch === ',') {
+      fields.push(cur);
+      cur = '';
+    } else cur += ch;
+  }
+  fields.push(cur);
+  return fields;
+}
+
+const csv = (await fetchText(AIRLINES)).replace(/^/, '');
+const tree = JSON.parse(await fetchText(TREE));
+if (tree.truncated) throw new Error('The standing-data tree came back truncated; the route sizes would be incomplete');
+
+// Bytes of route data per ICAO code: routes/schema-01/<letter>/<CODE>-all.csv or <CODE>-<digit>.csv.
+const routeBytes = new Map();
+for (const entry of tree.tree) {
+  const match = /^routes\/schema-01\/[A-Z0-9]\/([A-Z]{3})-(?:all|\d)\.csv$/.exec(entry.path);
+  if (!match) continue;
+  routeBytes.set(match[1], (routeBytes.get(match[1]) ?? 0) + (entry.size ?? 0));
+}
+
+const rows = csv.split(/\r?\n/);
+const header = parseLine(rows[0]);
+const ICAO = header.indexOf('ICAO');
+const IATA = header.indexOf('IATA');
+const candidates = new Map();
+for (const line of rows.slice(1)) {
+  if (!line.trim()) continue;
+  const fields = parseLine(line);
+  const icao = fields[ICAO]?.trim().toUpperCase();
+  const iata = fields[IATA]?.trim().toUpperCase();
+  if (!icao || !iata || !/^[A-Z]{3}$/.test(icao) || !/^(?=.*[A-Z])[A-Z0-9]{2}$/.test(iata)) continue;
+  const list = candidates.get(iata) ?? [];
+  if (!list.includes(icao)) list.push(icao);
+  candidates.set(iata, list);
+}
+
+const table = {};
+let shared = 0;
+let dropped = 0;
+for (const iata of [...candidates.keys()].sort()) {
+  const list = candidates.get(iata);
+  if (list.length === 1) {
+    table[iata] = list[0];
+    continue;
+  }
+  shared++;
+  const ranked = list
+    .map((icao) => ({ icao, bytes: routeBytes.get(icao) ?? 0 }))
+    .sort((a, b) => b.bytes - a.bytes || a.icao.localeCompare(b.icao));
+  if (ranked[0].bytes === 0) {
+    dropped++;
+    continue;
+  }
+  table[iata] = ranked[0].icao;
+}
+
+fs.writeFileSync(OUT, JSON.stringify(table));
+console.log(
+  `Wrote ${Object.keys(table).length} airline codes to ${OUT}; ${shared} shared IATA codes resolved by route data, ${dropped} left out without any`,
+);

server/scripts/repository-owners.json

@@ -40,6 +40,7 @@
   "DocumentSyncItems": "doc-sync",
   "FerrataTiles": "ferratas",
   "FileLinks": "files",
+  "FlightLiveStates": "flight-live",
   "GoogleApiUsage": "google-quota",
   "GooglePlacePhotoMeta": "place-photos",
   "HiddenCountries": "atlas",