refactor(Core/ServerMail): Refactor to Dedicated Manager Class with Multi-Item & Condition Support (#21590)

1. Core Cleanup
    - Move all ServerMail logic from `ObjectMgr` into a new dedicated `ServerMailMgr` class
    - Move faction logic for money from SendServerMail into the script
2. Separation of items into a new table
    - Create a new `mail_server_template_items` table
    - Allows to send multiple items in one mail
    - Separate items per faction Alliance/Horde
3. Separation of conditions into a new table
    - Create a new `mail_server_template_conditions` table
    - Allows to use multiple conditions for one mail
    - Available condition types
        - Minimum playtime (playerLevel >= condition)
        - Minimum playtime (playerPlayTime >= condition)
        - Rewarded quest
        - Earned achievement
        - Earned reputation (playerReputation >= conditionState)
        - Faction
        - Race
        - Class
4. Updated ServerMail loading
    - Move item and condition loading to their own functions
        - LoadMailServerTemplateItems()
        - LoadMailServerTemplateConditions()
5. Reworked eligibility check
    - Player needs to pass all conditions to be eligible for the mail
    - All players are automatically eligible if no conditions exist for a server mail template.
6. Updated foreign keys
    - For table `mail_server_character`, `mail_server_template_conditions`, `mail_server_template_items` foreign key with on delete cascade is added for automatic removal of entries if mail_server_template.id is deleted.
7. Database changes
    - See the PR

src/server/scripts/Commands/cs_reload.cpp

@@ -38,6 +38,7 @@ EndScriptData */
 #include "MotdMgr.h"
 #include "ObjectMgr.h"
 #include "ScriptMgr.h"
+#include "ServerMailMgr.h"
 #include "SkillDiscovery.h"
 #include "SkillExtraItems.h"
 #include "SmartAI.h"
@@ -1196,7 +1197,7 @@ public:
     static bool HandleReloadMailServerTemplateCommand(ChatHandler* handler)
     {
         LOG_INFO("server.loading", "Reloading `server_mail_template` table");
-        sObjectMgr->LoadMailServerTemplates();
+        sServerMailMgr->LoadMailServerTemplates();
         handler->SendGlobalGMSysMessage("DB table `server_mail_template` reloaded.");
         return true;
     }

src/server/scripts/World/server_mail.cpp

@@ -16,10 +16,10 @@
  */
 
 #include "CreatureScript.h"
-#include "ObjectMgr.h"
 #include "Player.h"
 #include "PlayerScript.h"
 #include "QueryResult.h"
+#include "ServerMailMgr.h"
 
 class ServerMailReward : public PlayerScript
 {
@@ -30,13 +30,14 @@ public:
     void OnPlayerLogin(Player* player) override
     {
         // Retrieve all server mail records and session only once
-        auto const& serverMailStore = sObjectMgr->GetAllServerMailStore();
+        auto const& serverMailStore = sServerMailMgr->GetAllServerMailStore();
         WorldSession* session = player->GetSession();
         // We should always have a session, just incase
         if (!session)
             return;
 
         uint32 playerGUID = player->GetGUID().GetCounter();
+        bool isAlliance = player->GetTeamId() == TEAM_ALLIANCE;
 
         for (auto const& [mailId, servMail] : serverMailStore)
         {
@@ -45,26 +46,24 @@ public:
             stmt->SetData(1, mailId);
 
             // Capture servMail by value
-            auto callback = [session, servMailWrapper = std::reference_wrapper<ServerMail const>(servMail)](PreparedQueryResult result)
+            auto callback = [session, servMailWrapper = std::reference_wrapper<ServerMail const>(servMail), isAlliance](PreparedQueryResult result)
                 {
-                     ServerMail const& servMail = servMailWrapper.get();  // Dereference the wrapper to get the original object
+                    ServerMail const& servMail = servMailWrapper.get();  // Dereference the wrapper to get the original object
 
                     if (!result)
                     {
-                        sObjectMgr->SendServerMail(
+                        uint32 money = isAlliance ? servMail.moneyA : servMail.moneyH;
+                        std::vector<ServerMailItems> const& items = isAlliance ? servMail.itemsA : servMail.itemsH;
+                        std::vector<ServerMailCondition> const& conditions = servMail.conditions;
+
+                        sServerMailMgr->SendServerMail(
                             session->GetPlayer(),
                             servMail.id,
-                            servMail.reqLevel,
-                            servMail.reqPlayTime,
-                            servMail.moneyA,
-                            servMail.moneyH,
-                            servMail.itemA,
-                            servMail.itemCountA,
-                            servMail.itemH,
-                            servMail.itemCountH,
+                            money,
+                            items,
+                            conditions,
                             servMail.subject,
-                            servMail.body,
-                            servMail.active
+                            servMail.body
                         );
                     }
                 };