feat(tasks): a task can repeat every N days from a dated start

A third period, { unit: "cycle", days, from }, cut in day-key space like
weeks and months, so each game's per-server reset carries over. Tasks on
it are tallied and switched apart (showCycleTasks, on by default), show
the days left in their chip, and the lower row's heading now names the
periods it holds.

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

src/shared/task.ts

@@ -6,7 +6,7 @@ import { periodOf, PeriodSchema } from "./period.ts";
 import type { Region } from "./schema.ts";
 
 /**
- * Weekly and monthly chores the reader sets up per game — ZZZ's weekly
+ * Weekly, monthly and every-N-days chores the reader sets up per game — ZZZ's weekly
  * activity points, Endfield's weekly routine.
  *
  * Not events: no window, no end, no done or ignored. A task is a period that
@@ -110,12 +110,22 @@ function ordinal(n: number): string {
   return `${n}${["th", "st", "nd", "rd"][n % 10] ?? "th"}`;
 }
 
+const MONTHS = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];
+
+/** `2025-12-02` → `2 Dec 2025`: the same in every locale, so it reads the same wherever it is quoted. */
+export function asOfLabel(day: string): string {
+  const [y, m, d] = day.split("-").map(Number);
+  return `${d} ${MONTHS[(m ?? 1) - 1]} ${y}`;
+}
+
 /** One line saying when it rolls and what it wants. */
 export function taskCaption(task: Pick<Task, "period" | "measure">): string {
   const when =
     task.period.unit === "week"
       ? `every week from ${WEEKDAYS[task.period.startsOn - 1]}`
-      : `every month from the ${ordinal(task.period.startsOn)}`;
+      : task.period.unit === "month"
+        ? `every month from the ${ordinal(task.period.startsOn)}`
+        : `every ${task.period.days} days from ${asOfLabel(task.period.from)}`;
   const m = task.measure;
   const what =
     m.kind === "amount"