feat: T4 waves 1-2 - rule configs, schema, suggestions core, season, rule forms

- Rule configs with typed parsers and registry; Berlin day helpers
- Schema: T4 enums, Suggestion table, feed vocabulary (feedStatus as
  ColonyCondition with legacy text mapping), split queen source,
  varroa sample size; migration harness for data migrations
- SuggestionsService: propose/refresh/resolve/obsolete/expire,
  accept/dismiss/reopen incl. bulk, lock order, concurrency e2e
- SeasonService: phenology-based segments, inspection/varroa due dates,
  queen age; TimeEventsStep with JobPartialFailure
- Frontend: per-rule settings forms with visible value sources

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

ApiCore-Backend/src/common/dates.ts

@@ -0,0 +1,101 @@
+const BERLIN_TIME_ZONE = 'Europe/Berlin';
+const MS_PER_DAY = 86_400_000;
+const DAY_PATTERN = /^\d{4}-\d{2}-\d{2}$/;
+const TIME_PATTERN = /^([01]\d|2[0-3]):([0-5]\d)$/;
+
+// en-CA formats a date as YYYY-MM-DD.
+const berlinDayFormat = new Intl.DateTimeFormat('en-CA', {
+  timeZone: BERLIN_TIME_ZONE,
+  year: 'numeric',
+  month: '2-digit',
+  day: '2-digit',
+});
+
+const berlinPartsFormat = new Intl.DateTimeFormat('en-GB', {
+  timeZone: BERLIN_TIME_ZONE,
+  hourCycle: 'h23',
+  year: 'numeric',
+  month: '2-digit',
+  day: '2-digit',
+  hour: '2-digit',
+  minute: '2-digit',
+  second: '2-digit',
+});
+
+/** The calendar day (YYYY-MM-DD) of an instant in Europe/Berlin. */
+export function berlinDayOf(instant: Date): string {
+  return berlinDayFormat.format(instant);
+}
+
+/** Today's calendar day (YYYY-MM-DD) in Europe/Berlin. */
+export function berlinToday(now: Date = new Date()): string {
+  return berlinDayOf(now);
+}
+
+/** A stored day (YYYY-MM-DD) as the DateTime used for dates: midnight UTC. */
+export function dayToDate(day: string): Date {
+  if (!DAY_PATTERN.test(day)) {
+    throw new Error(`Invalid day: ${day}`);
+  }
+  const date = new Date(`${day}T00:00:00.000Z`);
+  // 2026-02-30 parses to March 2nd: only a day that round-trips exists.
+  if (Number.isNaN(date.getTime()) || date.toISOString().slice(0, 10) !== day) {
+    throw new Error(`Invalid day: ${day}`);
+  }
+  return date;
+}
+
+function dayNumber(day: string): number {
+  return Math.round(dayToDate(day).getTime() / MS_PER_DAY);
+}
+
+/** Calendar arithmetic on YYYY-MM-DD strings; no time zone involved. */
+export function addDays(day: string, days: number): string {
+  const result = new Date(dayToDate(day).getTime() + days * MS_PER_DAY);
+  return result.toISOString().slice(0, 10);
+}
+
+/** Whole calendar days from `from` to `to` (negative when `to` is earlier). */
+export function daysBetween(from: string, to: string): number {
+  return dayNumber(to) - dayNumber(from);
+}
+
+/** Offset of Europe/Berlin to UTC at an instant, in milliseconds. */
+function berlinOffsetMs(instant: Date): number {
+  const parts: Record<string, number> = {};
+  for (const part of berlinPartsFormat.formatToParts(instant)) {
+    if (part.type !== 'literal') {
+      parts[part.type] = Number(part.value);
+    }
+  }
+  const asUtc = Date.UTC(
+    parts.year,
+    parts.month - 1,
+    parts.day,
+    parts.hour,
+    parts.minute,
+    parts.second,
+  );
+  // The instant without its milliseconds: the formatter works in seconds.
+  return asUtc - Math.floor(instant.getTime() / 1000) * 1000;
+}
+
+/**
+ * The instant at which the Berlin wall clock shows `day` `hhmm`. The offset
+ * is taken at the target day itself (applied twice, so the day a clock change
+ * happens comes out right): 06:30 is 04:30Z in summer and 05:30Z in winter.
+ */
+export function berlinDateTime(day: string, hhmm: string): Date {
+  const time = TIME_PATTERN.exec(hhmm);
+  if (!time) {
+    throw new Error(`Invalid time: ${hhmm}`);
+  }
+  const wallClockAsUtc =
+    dayToDate(day).getTime() +
+    (Number(time[1]) * 60 + Number(time[2])) * 60_000;
+  let instant = new Date(
+    wallClockAsUtc - berlinOffsetMs(new Date(wallClockAsUtc)),
+  );
+  instant = new Date(wallClockAsUtc - berlinOffsetMs(instant));
+  return instant;
+}