feat(editor): add WANV (Anniversary & Recurring Events) — 121st open format

Novel replacement for the implicit recurring-event
scheduler vanilla WoW encoded across the GameEvent SQL
table + per-holiday script hooks. Each entry binds one
calendar-driven recurring event (yearly holiday like
Hallow's End, monthly tribute day, weekly Double XP
Weekend, anniversary celebration) to its scheduling
rule and its payload (a spell buff applied to all
online players, a gift item granted on first event-
window login).

Eight eventKind values (Holiday / Anniversary /
DoubleXP / DoubleHonor / PetBattleWeekend /
BattlegroundBonus / SeasonalQuest / Misc) and four
recurrenceKind values (Yearly / Monthly / Weekly /
OneOff). The startDay field is polymorphic per
recurrenceKind: Yearly/Monthly/OneOff use it as
1..31 day-of-month, Weekly uses it as 0..6 weekday
(Sun..Sat) — the validator enforces both ranges per
kind.

Three preset emitters: makeStandardHolidays (5 yearly
holidays with realistic spell+item payload bindings —
Hallow's End spell 24710, Winter Veil 26157, Brewfest
42500, etc.), makeBonusEvents (4 weekly recurring
bonuses — Friday triple-day weekends and Saturday-
Sunday double-day pet-battle bonus), makeAnniversary
(3 game-launch anniversaries — WoW Nov 23 / TBC Jan 16
/ WotLK Nov 13 with overlapping celebration windows).

Validator's most novel checks combine calendar +
recurrence semantics: per-kind schedule validity (Weekly
startDay 0..6 weekday, durationDays <= 7 to prevent
self-overlap; Yearly/Monthly/OneOff startMonth 1..12,
startDay 1..31 with calendar sanity — Feb cap at 29,
Apr/Jun/Sep/Nov cap at 30 for "no Feb 30" / "no Apr 31"
errors).

Format count 120 -> 121. CLI flag count 1269 -> 1274.

tools/editor/cli_format_table.cpp

@@ -123,6 +123,7 @@ constexpr FormatMagicEntry kFormats[] = {
     {{'W','L','M','A'}, ".wlma",  "loot",      "--info-wlma",      "Loot mode policy catalog"},
     {{'W','S','K','P'}, ".wskp",  "world",     "--info-wskp",      "Sky parameters catalog"},
     {{'W','C','F','G'}, ".wcfg",  "server",    "--info-wcfg",      "Server config catalog"},
+    {{'W','A','N','V'}, ".wanv",  "events",    "--info-wanv",      "Anniversary & recurring event catalog"},
     {{'W','F','A','C'}, ".wfac",  "factions",  nullptr,            "Faction catalog"},
     {{'W','L','C','K'}, ".wlck",  "locks",     nullptr,            "Lock catalog"},
     {{'W','S','K','L'}, ".wskl",  "skills",    nullptr,            "Skill catalog"},