feat(Scripts): Add hooks to allow modules to override arena rating updates

Add two new ArenaScript hooks to prevent module conflicts:

- OnBeforeArenaTeamMemberUpdate: Allows modules to skip core's
  MemberWon/MemberLost rating calculations by returning true

- CanSaveArenaStatsForMember: Allows modules to prevent core from
  writing to character_arena_stats table by returning false

Hook locations:
- Arena.cpp: Wrap MemberWon/MemberLost calls (lines 358, 366)
- ArenaTeam.cpp: Wrap character_arena_stats DB write (line 969)

Use case: Modules implementing alternative rating systems (like Glicko-2)
can now completely override core arena ratings without database conflicts
or redundant calculations.

When hooks return default values (false/true respectively), core behavior
is unchanged, maintaining backward compatibility.

src/server/game/Battlegrounds/Arena.cpp

@@ -355,12 +355,18 @@ void Arena::EndBattleground(TeamId winnerTeamId)
                             player->CastSpell(player, SPELL_LAST_MAN_STANDING, true);
                         }
 
-                        winnerArenaTeam->MemberWon(player, loserMatchmakerRating, winnerMatchmakerChange);
+                        if (!sScriptMgr->OnBeforeArenaTeamMemberUpdate(winnerArenaTeam, player, true, loserMatchmakerRating, winnerMatchmakerChange))
+                        {
+                            winnerArenaTeam->MemberWon(player, loserMatchmakerRating, winnerMatchmakerChange);
+                        }
                     }
                 }
                 else
                 {
-                    loserArenaTeam->MemberLost(player, winnerMatchmakerRating, loserMatchmakerChange);
+                    if (!sScriptMgr->OnBeforeArenaTeamMemberUpdate(loserArenaTeam, player, false, winnerMatchmakerRating, loserMatchmakerChange))
+                    {
+                        loserArenaTeam->MemberLost(player, winnerMatchmakerRating, loserMatchmakerChange);
+                    }
 
                     // Arena lost => reset the win_rated_arena having the "no_lose" condition
                     player->ResetAchievementCriteria(ACHIEVEMENT_CRITERIA_CONDITION_NO_LOSE, 0);

src/server/game/Battlegrounds/ArenaTeam.cpp

@@ -966,12 +966,15 @@ void ArenaTeam::SaveToDB(bool forceMemberSave)
         stmt->SetData(6, itr->Guid.GetCounter());
         trans->Append(stmt);
 
-        stmt = CharacterDatabase.GetPreparedStatement(CHAR_REP_CHARACTER_ARENA_STATS);
-        stmt->SetData(0, itr->Guid.GetCounter());
-        stmt->SetData(1, GetSlot());
-        stmt->SetData(2, itr->MatchMakerRating);
-        stmt->SetData(3, itr->MaxMMR);
-        trans->Append(stmt);
+        if (sScriptMgr->CanSaveArenaStatsForMember(this, itr->Guid))
+        {
+            stmt = CharacterDatabase.GetPreparedStatement(CHAR_REP_CHARACTER_ARENA_STATS);
+            stmt->SetData(0, itr->Guid.GetCounter());
+            stmt->SetData(1, GetSlot());
+            stmt->SetData(2, itr->MatchMakerRating);
+            stmt->SetData(3, itr->MaxMMR);
+            trans->Append(stmt);
+        }
     }
 
     CharacterDatabase.CommitTransaction(trans);

src/server/game/Scripting/ScriptDefines/ArenaScript.cpp

@@ -44,6 +44,16 @@ void ScriptMgr::OnArenaStart(Battleground* bg)
     CALL_ENABLED_HOOKS(ArenaScript, ARENAHOOK_ON_ARENA_START, script->OnArenaStart(bg));
 }
 
+bool ScriptMgr::OnBeforeArenaTeamMemberUpdate(ArenaTeam* team, Player* player, bool won, uint32 opponentMatchmakerRating, int32 matchmakerChange)
+{
+    CALL_ENABLED_BOOLEAN_HOOKS(ArenaScript, ARENAHOOK_ON_BEFORE_TEAM_MEMBER_UPDATE, script->OnBeforeArenaTeamMemberUpdate(team, player, won, opponentMatchmakerRating, matchmakerChange));
+}
+
+bool ScriptMgr::CanSaveArenaStatsForMember(ArenaTeam* team, ObjectGuid playerGuid)
+{
+    CALL_ENABLED_BOOLEAN_HOOKS(ArenaScript, ARENAHOOK_CAN_SAVE_ARENA_STATS_FOR_MEMBER, !script->CanSaveArenaStatsForMember(team, playerGuid));
+}
+
 ArenaScript::ArenaScript(const char* name, std::vector<uint16> enabledHooks)
     : ScriptObject(name, ARENAHOOK_END)
 {

src/server/game/Scripting/ScriptDefines/ArenaScript.h

@@ -29,6 +29,8 @@ enum ArenaHook
     ARENAHOOK_CAN_SAVE_TO_DB,
     ARENAHOOK_ON_BEFORE_CHECK_WIN_CONDITION,
     ARENAHOOK_ON_ARENA_START,
+    ARENAHOOK_ON_BEFORE_TEAM_MEMBER_UPDATE,
+    ARENAHOOK_CAN_SAVE_ARENA_STATS_FOR_MEMBER,
     ARENAHOOK_END
 };
 
@@ -51,6 +53,10 @@ public:
     [[nodiscard]] virtual bool CanSaveToDB(ArenaTeam* /*team*/) { return true; }
 
     virtual void OnArenaStart(Battleground* /* bg */) { };
+
+    [[nodiscard]] virtual bool OnBeforeArenaTeamMemberUpdate(ArenaTeam* /*team*/, Player* /*player*/, bool /*won*/, uint32 /*opponentMatchmakerRating*/, int32 /*matchmakerChange*/) { return false; }
+
+    [[nodiscard]] virtual bool CanSaveArenaStatsForMember(ArenaTeam* /*team*/, ObjectGuid /*playerGuid*/) { return true; }
 };
 
 #endif

src/server/game/Scripting/ScriptMgr.h

@@ -660,6 +660,8 @@ public: /* ArenaScript */
     bool CanSaveToDB(ArenaTeam* team);
     bool OnBeforeArenaCheckWinConditions(Battleground* const bg);
     void OnArenaStart(Battleground* const bg);
+    bool OnBeforeArenaTeamMemberUpdate(ArenaTeam* team, Player* player, bool won, uint32 opponentMatchmakerRating, int32 matchmakerChange);
+    bool CanSaveArenaStatsForMember(ArenaTeam* team, ObjectGuid playerGuid);
 
 public: /* MiscScript */