feat(pipeline): add WSET (Wowee Item Set / Tier Bonus) catalog

51st open format — replaces ItemSet.dbc + ItemSetSpell.dbc
plus the AzerothCore-style item_set_spell SQL data. Closes
the tier-bonus gap left by WIT (which describes individual
items but not the set bonuses they grant when worn together).

Each entry binds up to 8 piece item IDs to up to 4 bonus
thresholds — at N pieces worn, the matching bonus spell
activates as an aura. Standard 2/4/6/8-piece tier set pattern
is the canonical case; 5-piece PvP sets with 2/4 bonuses are
also supported.

Cross-references with prior formats — itemIds[] point at
WIT.itemId, bonusSpellIds[] point at WSPL.spellId, and
requiredSkillId points at WSKL.skillId. requiredClassMask
is a 32-bit field (uint32_t) so bit positions match WCHC's
classId enum directly — Druid (bit 11 = 0x800) and Mage
(bit 8 = 0x100) wouldn't fit in a uint8_t.

CLI: --gen-itset (2 raid sets — Battlegear of Wrath +
Stormrage Raiment, real WoW item/spell IDs), --gen-itset-tier
(4 tier-1 progression sets covering plate / cloth / leather /
holy plate), --gen-itset-pvp (3 PvP gladiator 5-piece sets
with honor-rank skill thresholds), --info-wset, --validate-wset
with --json variants. Validator catches id+name+pieceCount
required, pieceCount/bonusCount within array bounds, piece-
slot drift (0 IDs within count or non-0 IDs past count),
bonus thresholds strictly ascending, no bonus threshold
exceeding pieceCount (would never trigger), and spellId=0
in any populated bonus slot.

Format graph: 50 → 51 binary formats. CLI flag count: 762
→ 767.

tools/editor/cli_arg_required.cpp

@@ -154,6 +154,8 @@ const char* const kArgRequired[] = {
     "--gen-ceq", "--gen-ceq-bosses", "--gen-ceq-ranged",
     "--info-wceq", "--validate-wceq",
     "--export-wceq-json", "--import-wceq-json",
+    "--gen-itset", "--gen-itset-tier", "--gen-itset-pvp",
+    "--info-wset", "--validate-wset",
     "--gen-weather-temperate", "--gen-weather-arctic",
     "--gen-weather-desert", "--gen-weather-stormy",
     "--gen-zone-atmosphere",