feat(pipeline): add WMAL (Wowee Mail Template) format

Novel open replacement for AzerothCore-style
mail_loot_template SQL + the in-game mail subset of the
inventory + currency systems. The 34th open format added
to the editor.

Defines templated mail messages with currency + item
attachments. Triggered by quest reward delivery (overflow
when bag is full), auction house bid wins / sales,
achievement reward attachments, GM correspondence, holiday
event mailings (Brewfest samples, Hallow's End candy), and
returned-mail-on-rejection.

Cross-references with previously-added formats:
  WMAL.entry.senderNpcId        -> WCRT.entry.creatureId
  WMAL.entry.attachments.itemId -> WIT.entry.itemId

Format:
  • magic "WMAL", version 1, little-endian
  • per template: templateId / senderNpcId / subject / body /
    senderName / moneyCopperAttached / categoryId / cod /
    returnable / expiryDays / attachments[] (each: itemId +
    quantity)

Enums:
  • Category (8): QuestReward / Auction / GmCorrespondence /
                   AchievementReward / EventMailing / Raffle /
                   ScriptDelivery / ReturnedMail

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

Three preset emitters showcase typical mail templates:
  • makeStarter — 3 templates (quest overflow / auction won /
                   GM gift) covering the 3 most common
                   categories
  • makeHoliday — 4 holiday samples that cross-reference the
                   WTKN seasonal token IDs (200=Tricky Treats,
                   201=Brewfest, 202=Coin of Ancestry,
                   203=Stranger's Gift) so the demo content
                   stack ships a full holiday onboarding
                   experience
  • makeAuction — 5-template auction-house family (outbid /
                   won / sold / expired / cancelled) — runtime
                   fills in actual bid amounts / sold items
                   at send time

CLI added (5 flags, 635 documented total now):
  --gen-mail / --gen-mail-holiday / --gen-mail-auction
  --info-wmal / --validate-wmal

Validator catches: templateId=0 + duplicates, empty subject,
neither senderNpcId nor senderName set (no displayable
sender), unknown category, expiryDays=0 (mail expires
immediately), cod=1 with no money attached (free COD),
empty mail in categories where the runtime doesn't fill in
content (skips Auction / GmCorrespondence / ReturnedMail
where empty templates are intentional).

Two bugs caught + fixed during smoke-test on the auction
preset:
  • print formatting glued the `0` from senderNpcId after
    the senderName when no NPC was set (rendered as
    "Postmaster0" instead of "Postmaster") — fixed with an
    explicit if/else split
  • validator's "no money + no items" warning was too
    aggressive for the Auction category, where templates
    are intentionally informational and the runtime fills
    in the real values — added Auction + ReturnedMail to
    the skip list

include/pipeline/wowee_mail.hpp

@@ -0,0 +1,109 @@
+#pragma once
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace wowee {
+namespace pipeline {
+
+// Wowee Open Mail Template catalog (.wmal) — novel
+// replacement for AzerothCore-style mail_loot_template SQL
+// + the in-game mail subset of the inventory + currency
+// systems. The 34th open format added to the editor.
+//
+// Defines templated mail messages with currency + item
+// attachments. Triggered by:
+//   • quest reward delivery (overflow mail when bag is full)
+//   • auction house bid wins / sales completion
+//   • achievement reward attachments
+//   • GM correspondence
+//   • holiday event mailings (Brewfest samples, Hallow's End
+//     candy, anniversary thank-you notes)
+//   • returned-mail-on-rejection
+//
+// Cross-references with previously-added formats:
+//   WMAL.entry.senderNpcId           → WCRT.entry.creatureId
+//   WMAL.entry.attachments.itemId    → WIT.entry.itemId
+//
+// Binary layout (little-endian):
+//   magic[4]            = "WMAL"
+//   version (uint32)    = current 1
+//   nameLen + name (catalog label)
+//   entryCount (uint32)
+//   entries (each):
+//     templateId (uint32)
+//     senderNpcId (uint32)
+//     subjectLen + subject
+//     bodyLen + body
+//     senderLen + senderName
+//     moneyCopperAttached (uint32)
+//     attachmentCount (uint8) / categoryId (uint8) /
+//       cod (uint8) / returnable (uint8)
+//     expiryDays (uint16) / pad[2]
+//     attachments (each: itemId (uint32) + quantity (uint16) + pad[2])
+struct WoweeMail {
+    enum Category : uint8_t {
+        QuestReward     = 0,
+        Auction         = 1,
+        GmCorrespondence = 2,
+        AchievementReward = 3,
+        EventMailing    = 4,
+        Raffle          = 5,
+        ScriptDelivery  = 6,
+        ReturnedMail    = 7,
+    };
+
+    struct Attachment {
+        uint32_t itemId = 0;
+        uint16_t quantity = 1;
+    };
+
+    struct Entry {
+        uint32_t templateId = 0;
+        uint32_t senderNpcId = 0;       // 0 = system / no NPC
+        std::string subject;
+        std::string body;
+        std::string senderName;          // fallback when senderNpcId=0
+        uint32_t moneyCopperAttached = 0;
+        uint8_t categoryId = QuestReward;
+        uint8_t cod = 0;                 // 1 = cash on delivery
+        uint8_t returnable = 1;          // 1 = unread mail returns
+        uint16_t expiryDays = 30;
+        std::vector<Attachment> attachments;
+    };
+
+    std::string name;
+    std::vector<Entry> entries;
+
+    bool isValid() const { return !entries.empty(); }
+
+    const Entry* findById(uint32_t templateId) const;
+
+    static const char* categoryName(uint8_t c);
+};
+
+class WoweeMailLoader {
+public:
+    static bool save(const WoweeMail& cat,
+                     const std::string& basePath);
+    static WoweeMail load(const std::string& basePath);
+    static bool exists(const std::string& basePath);
+
+    // Preset emitters used by --gen-mail* variants.
+    //
+    //   makeStarter — 3 templates covering quest reward
+    //                  overflow / auction house / GM gift.
+    //   makeHoliday — 4 holiday-event mailings tied to WSEA
+    //                  yearly events (Tricky Treats sample
+    //                  pack, Brewfest sampler, Lunar Festival
+    //                  blessing, Winter's Veil gift box).
+    //   makeAuction — full auction-house template family:
+    //                  outbid / won / sold / expired / cancelled.
+    static WoweeMail makeStarter(const std::string& catalogName);
+    static WoweeMail makeHoliday(const std::string& catalogName);
+    static WoweeMail makeAuction(const std::string& catalogName);
+};
+
+} // namespace pipeline
+} // namespace wowee