Add .transmog check diagnostic command

[Nyeriah]

Summary

• Adds .transmog check <player> <destItem> <srcItem> — a GM/console command that audits whether a given destination/source item pair could be transmogged for a target player, and reports which rules fail.
• Works for offline characters and from the console: the handler resolves the target through CharacterCache and falls back to direct character_skills / character_spell reads when no Player* is available. The collection check uses the account-keyed collectionCache, which is loaded regardless of who's online.
• Output is grouped into three sections (Pair / Per-item / Collection) plus a final verdict. Each section prints one line: [+] all checks passed, [-] one or more failures (semicolon-separated), or [~] whitelisted/disabled-system skip. Plain text — no color codes — so it stays readable on the worldserver console.

What's covered by the checks

• Pair: same ItemId, same DisplayInfoID, item-class match, forbidden inventory types (bag/relic/ring/trinket/ammo/quiver), ranged-vs-melee mismatch, subclass/inv-type mismatch via the existing IsSubclassMismatchAllowed / IsInvTypeMismatchAllowed helpers.
• Per-item (run for both src and dest): whitelist short-circuit, valid armor/weapon class, blacklist, allowed quality, fishing-pole flag, holiday/event gate, zero-stat rejection, proficiency / required-skill / class / race / level / required-spell, all honoring the matching IgnoreReq* and AllowLowerTiers config toggles.
• Collection: respects GetUseCollectionSystem(); looks up the source ItemId in the account's collectionCache.

Strings

All new diagnostic strings (IDs 46–80, English + 8 locales: koKR/frFR/deDE/zhCN/zhTW/esES/esMX/ruRU) are appended to the existing data/sql/db-world/updates/2026_05_09_migrate_strings_to_module_string.sql migration, alongside the command table entry registering the subcommand at security level 2.

Known limitation

IsSubclassMismatchAllowed internally calls TierAvailable(player, 0, ...). For an offline target, player is null and playerGuid=0, so the AllowLowerTiers armor-mismatch path short-circuits to false. This can yield a false-negative "Subclass mismatch — not allowed" verdict in the narrow case of armor pairs with different subclasses where the offline player actually owns higher-tier armor. Easy to address in a follow-up by threading the guid through, but didn't want to widen the touched API surface in this PR.

Test plan

• .transmog check <online-name> <destId> <srcId> from chat: known-good pair returns === RESULT: CAN transmog ===.
• Same command via worldserver console for an offline player: produces a readable, color-free report.
• Each failure path triggers the correct section + message (e.g. ring as dest → forbidden inv type; ranged onto melee → ranged mismatch; level-locked item below the target's level → level fail line).
• Whitelisted source item: per-item section shows [~] Whitelisted — all requirement checks are bypassed.
• UseCollectionSystem=0: collection section shows [~] Collection system disabled; otherwise verifies presence in the account collection cache.
• AI tool usage disclosed: drafted with Claude Code assistance.