feat: v0.11.0 — map interactions per PLAN.md: expanded airport popup (approx local time + deterministic generated weather), animated plane markers from /api/state polls with status popups, active contract route lines (pending dashed vs in-flight solid); pure libs lib/weather.ts, lib/localTime.ts, lib/mapData.ts

lib/weather.ts

@@ -0,0 +1,47 @@
+import { mulberry32 } from './game/seed';
+
+// Pure deterministic per-airport weather (v0.11.0) — display-only per PLAN.md, no
+// gameplay effects. The same ICAO always yields the same weather (stable across
+// polls and sessions); an optional dayKey varies it by sim-day when wanted.
+
+export type WeatherCondition = 'Clear' | 'Cloudy' | 'Rain' | 'Fog';
+
+export interface AirportWeather {
+  condition: WeatherCondition;
+  // Meteorological convention: direction the wind blows FROM, degrees true [0, 360).
+  windDirDeg: number;
+  windKt: number;
+  visibilityM: number;
+}
+
+// FNV-1a 32-bit — cheap, stable string hash (no Math.random, no Date anywhere).
+function fnv1a(s: string): number {
+  let h = 0x811c9dc5;
+  for (let i = 0; i < s.length; i++) {
+    h ^= s.charCodeAt(i);
+    h = Math.imul(h, 0x01000193);
+  }
+  return h >>> 0;
+}
+
+export function weatherFor(icao: string, dayKey?: number): AirportWeather {
+  const seed = (fnv1a(icao) ^ (dayKey === undefined ? 0 : Math.imul(dayKey | 0, 0x9e3779b9))) >>> 0;
+  const rng = mulberry32(seed);
+
+  const c = rng();
+  let condition: WeatherCondition;
+  if (c < 0.45) condition = 'Clear';
+  else if (c < 0.75) condition = 'Cloudy';
+  else if (c < 0.92) condition = 'Rain';
+  else condition = 'Fog';
+
+  const windDirDeg = Math.floor(rng() * 360);
+  const windKt = Math.round(2 + rng() * 28); // 2–30 kt
+
+  let visibilityM: number;
+  if (condition === 'Fog') visibilityM = 500 + Math.floor(rng() * 1500); // 0.5–2 km
+  else if (condition === 'Rain') visibilityM = 4000 + Math.floor(rng() * 6000); // 4–10 km
+  else visibilityM = 8000 + Math.floor(rng() * 32000); // 8–40 km
+
+  return { condition, windDirDeg, windKt, visibilityM };
+}