feat(pipeline): add WSEA (Wowee Seasonal Event) format

Novel open replacement for Blizzard's GameEvents.dbc + the
AzerothCore-style game_event / game_event_creature /
game_event_gameobject SQL tables. The 31st open format
added to the editor.

Calendar-based content: holidays (Hallow's End, Winter's
Veil), recurring promotional events (Children's Week,
Lunar Festival, Brewfest), one-time anniversaries, and
XP-bonus weekends. Each event has a start date, duration,
optional recurrence (yearly / monthly / weekly), faction
restriction, optional XP bonus, and a reward currency
cross-reference into WTKN.

Cross-references with previously-added formats:
  WSEA.entry.tokenIdReward -> WTKN.entry.tokenId
                              (the seasonal currency the
                               event hands out — Tricky
                               Treats during Hallow's End,
                               Brewfest Tokens during
                               Brewfest, etc.)

The yearly preset's tokenIdReward values (200/201/202/203)
deliberately match WTKN.makeSeasonal's seasonal token ids
so the demo content stack already wires together: WSEA
yearly events grant WTKN tokens that vendors can charge in
via WTRN.item.extendedCost.

Format:
  • magic "WSEA", version 1, little-endian
  • per event: eventId / name / description / iconPath /
    announceMessage / startDate (Unix epoch seconds) /
    duration_seconds / recurrenceDays (0=one-shot, 365=yearly) /
    holidayKind / factionGroup / bonusXpPercent / tokenIdReward

Enums:
  • HolidayKind (7): Combat / Collection / Racial /
                     Anniversary / Fishing / Cosmetic /
                     WorldEvent
  • FactionGroup (3): Both / Alliance / Horde

API: WoweeEventLoader::save / load / exists / findById.

Three preset emitters showcase typical event shapes:
  • makeStarter       — 3 events covering Combat /
                         Fishing / Anniversary kinds
  • makeYearly        — 4 yearly holidays with full WTKN
                         cross-refs (Hallow's End / Brewfest /
                         Lunar Festival / Winter's Veil)
  • makeBonusWeekends — 3 monthly Fri-Sun bonus tiers
                         (50% / 100% / 200% RAF-style)

CLI added (5 flags, 614 documented total now):
  --gen-events / --gen-events-yearly / --gen-events-weekends
  --info-wsea / --validate-wsea

Validator catches: eventId=0 + duplicates, empty name,
unknown holidayKind / factionGroup, duration_seconds=0
(event never runs), duration > recurrence period (events
would overlap themselves on next iteration), bonusXpPercent
> 200 (very high — verify intentional).

tools/editor/cli_arg_required.cpp

@@ -88,6 +88,8 @@ const char* const kArgRequired[] = {
     "--export-wtrg-json", "--import-wtrg-json",
     "--gen-titles", "--gen-titles-pvp", "--gen-titles-achievement",
     "--info-wtit", "--validate-wtit",
+    "--gen-events", "--gen-events-yearly", "--gen-events-weekends",
+    "--info-wsea", "--validate-wsea",
     "--gen-weather-temperate", "--gen-weather-arctic",
     "--gen-weather-desert", "--gen-weather-stormy",
     "--gen-zone-atmosphere",