feat: mousearea, datetime dates, dir(), renpy.image_size and style.rebuild for Ren'Py games

Screens get an invisible mousearea that reports the pointer entering and leaving without taking
clicks. datetime.date/datetime/timedelta support construction and date arithmetic. dir() lists the
game's variables, renpy.style.rebuild() is a no-op, and renpy.image_size answers only for pictures
the browser already holds (otherwise an IOError the game can catch).

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

frontend/src/player/pymodules.ts

@@ -123,7 +123,58 @@ function strftime(format: string, d: Date): string {
 }
 
 const now = () => new DateTime(new Date());
+const DAY_MS = 86_400_000;
+
+/** `datetime.timedelta`: kept in milliseconds. */
+class TimeDelta {
+  constructor(public ms: number) {}
+  get days() { return Math.floor(this.ms / DAY_MS); }
+  get seconds() { return Math.floor((this.ms - this.days * DAY_MS) / 1000); }
+  total_seconds() { return this.ms / 1000; }
+  __binop__(op: string, other: any) {
+    if (op === "+" && other instanceof TimeDelta) return new TimeDelta(this.ms + other.ms);
+    if (op === "-" && other instanceof TimeDelta) return new TimeDelta(this.ms - other.ms);
+    if (op === "*" && typeof other === "number") return new TimeDelta(this.ms * other);
+    throw new TypeError(`timedelta ${op}`);
+  }
+}
+
+function timedelta(...a: any[]) {
+  const last = a[a.length - 1];
+  const kw = last && typeof last === "object" && last.__kw ? last.__kw : {};
+  const unit: Record<string, number> = { days: DAY_MS, seconds: 1000, minutes: 60_000, hours: 3_600_000,
+                                         weeks: 7 * DAY_MS, milliseconds: 1 };
+  let ms = typeof a[0] === "number" ? a[0] * DAY_MS : 0;
+  for (const [name, factor] of Object.entries(unit)) if (typeof kw[name] === "number") ms += kw[name] * factor;
+  return new TimeDelta(ms);
+}
+
+/** `date(y, m, d)` and `datetime(y, m, d, ...)`: a DateTime at a given moment, with date arithmetic. */
+const fromParts = (...a: any[]) => {
+  const [y, m, d, h = 0, min = 0, s = 0] = a.filter((x) => typeof x === "number");
+  const date = new Date(y, m - 1, d, h, min, s);
+  if (date.getMonth() !== m - 1 || date.getDate() !== d) throw new Error("ValueError: day is out of range for month");
+  return new DateTime(date);
+};
 const datetimeClass = { now, today: now, utcnow: now };
+const dateClass = Object.assign(fromParts, datetimeClass);
+Object.assign(DateTime.prototype, {
+  __binop__(this: DateTime, op: string, other: any) {
+    if (other instanceof TimeDelta && (op === "+" || op === "-")) {
+      const moved = new Date(this.d.getTime());
+      moved.setTime(moved.getTime() + (op === "+" ? other.ms : -other.ms));
+      // whole days keep the wall-clock time across daylight-saving changes
+      if (other.ms % DAY_MS === 0) {
+        const shifted = new Date(this.d.getTime());
+        shifted.setDate(shifted.getDate() + (op === "+" ? 1 : -1) * (other.ms / DAY_MS));
+        return new DateTime(shifted);
+      }
+      return new DateTime(moved);
+    }
+    if (other instanceof DateTime && op === "-") return new TimeDelta(this.d.getTime() - other.d.getTime());
+    throw new TypeError(`datetime ${op}`);
+  },
+});
 
 /** Namespaces added to the sandbox's builtins. */
 export function pythonModules(): Record<string, any> {
@@ -172,7 +223,7 @@ export function pythonModules(): Record<string, any> {
       sleep: () => null,
       strftime: (format: string, t?: any) => strftime(format, t instanceof DateTime ? t.d : new Date()),
     },
-    datetime: Object.assign({ datetime: datetimeClass, date: datetimeClass }, datetimeClass),
+    datetime: Object.assign({ datetime: dateClass, date: dateClass, timedelta }, datetimeClass),
     collections: {
       defaultdict: (factory?: any) => new PyDefaultDict(typeof factory === "function" ? () => factory() : null),
       OrderedDict: () => new PyDict(),