feat(Core/Command): add GM spectator to allow cross-faction /follow (#22393)

data/sql/updates/pending_db_world/rev_1751234046378828666.sql

@@ -0,0 +1,5 @@
+--
+DELETE FROM `acore_string` WHERE `entry` IN (6617, 6618);
+INSERT INTO `acore_string` (`entry`, `content_default`) VALUES
+(6617, 'GM Spectator is ON'),
+(6618, 'GM Spectator is OFF');

src/server/game/Entities/Player/Player.h

@@ -597,6 +597,7 @@ enum PlayerExtraFlags
     PLAYER_EXTRA_SPECTATOR_ON       = 0x0080,               // Marks if player is spectactor
     PLAYER_EXTRA_PVP_DEATH          = 0x0100,               // store PvP death status until corpse creating.
     PLAYER_EXTRA_SHOW_DK_PET        = 0x0400,               // Marks if player should see ghoul on login screen
+    PLAYER_EXTRA_GM_SPECTATOR       = 0x0800,
 };
 
 // 2^n values
@@ -1177,6 +1178,9 @@ public:
     void SetGameMaster(bool on);
     [[nodiscard]] bool isGMChat() const { return m_ExtraFlags & PLAYER_EXTRA_GM_CHAT; }
     void SetGMChat(bool on) { if (on) m_ExtraFlags |= PLAYER_EXTRA_GM_CHAT; else m_ExtraFlags &= ~PLAYER_EXTRA_GM_CHAT; }
+    [[nodiscard]] bool IsGMSpectator() const { return m_ExtraFlags & PLAYER_EXTRA_GM_SPECTATOR; }
+    void SetGMSpectator(bool on) { if (on) m_ExtraFlags |= PLAYER_EXTRA_GM_SPECTATOR; else m_ExtraFlags &= ~PLAYER_EXTRA_GM_SPECTATOR; }
+
     [[nodiscard]] bool isTaxiCheater() const { return m_ExtraFlags & PLAYER_EXTRA_TAXICHEAT; }
     void SetTaxiCheater(bool on) { if (on) m_ExtraFlags |= PLAYER_EXTRA_TAXICHEAT; else m_ExtraFlags &= ~PLAYER_EXTRA_TAXICHEAT; }
     [[nodiscard]] bool isGMVisible() const { return !(m_ExtraFlags & PLAYER_EXTRA_GM_INVISIBLE); }

src/server/game/Entities/Unit/Unit.cpp

@@ -20791,6 +20791,10 @@ void Unit::PatchValuesUpdate(ByteBuffer& valuesUpdateBuf, BuildValuesCachePosPoi
         {
             valuesUpdateBuf.put(posPointers.UnitFieldFactionTemplatePos, uint32(target->GetFaction()));
         }
+        else if (target->IsGMSpectator() && IsControlledByPlayer())
+        {
+            valuesUpdateBuf.put(posPointers.UnitFieldFactionTemplatePos, uint32(target->GetFaction()));
+        }
     }
 
     sScriptMgr->OnPatchValuesUpdate(this, valuesUpdateBuf, posPointers, target);

src/server/game/Miscellaneous/Language.h

@@ -1171,8 +1171,10 @@ enum AcoreStrings
     LANG_GM_ANNOUNCE_COLOR               = 6615,
 
     LANG_GM_SILENCE                      = 6616,              // "Silence is ON for %s" - Spell 1852
+    LANG_GM_SPECTATOR_ON                 = 6617,
+    LANG_GM_SPECTATOR_OFF                = 6618,
 
-    // Free strings 6617-7522
+    // Free strings 6619-7522
 
     LANG_WORLD_CLOSED                    = 7523,
     LANG_WORLD_OPENED                    = 7524,

src/server/scripts/Commands/cs_gm.cpp

@@ -38,13 +38,14 @@ public:
     {
         static ChatCommandTable gmCommandTable =
         {
-            { "chat",    HandleGMChatCommand,       SEC_GAMEMASTER,     Console::No  },
+            { "chat",      HandleGMChatCommand,       SEC_GAMEMASTER,     Console::No  },
-            { "fly",     HandleGMFlyCommand,        SEC_GAMEMASTER,     Console::No  },
+            { "fly",       HandleGMFlyCommand,        SEC_GAMEMASTER,     Console::No  },
-            { "ingame",  HandleGMListIngameCommand, SEC_PLAYER,         Console::Yes },
+            { "ingame",    HandleGMListIngameCommand, SEC_PLAYER,         Console::Yes },
-            { "list",    HandleGMListFullCommand,   SEC_ADMINISTRATOR,  Console::Yes },
+            { "list",      HandleGMListFullCommand,   SEC_ADMINISTRATOR,  Console::Yes },
-            { "visible", HandleGMVisibleCommand,    SEC_GAMEMASTER,     Console::No  },
+            { "visible",   HandleGMVisibleCommand,    SEC_GAMEMASTER,     Console::No  },
-            { "on",      HandleGMOnCommand,         SEC_MODERATOR,      Console::No  },
+            { "on",        HandleGMOnCommand,         SEC_MODERATOR,      Console::No  },
-            { "off",     HandleGMOffCommand,        SEC_MODERATOR,      Console::No  }
+            { "off",       HandleGMOffCommand,        SEC_MODERATOR,      Console::No  },
+            { "spectator", HandleGMSpectatorCommand,  SEC_GAMEMASTER,     Console::No  },
         };
         static ChatCommandTable commandTable =
         {
@@ -236,6 +237,19 @@ public:
         handler->SendNotification(LANG_GM_OFF);
         return true;
     }
+
+    static bool HandleGMSpectatorCommand(ChatHandler* handler, Optional<bool> enable)
+    {
+        Player* player = handler->GetSession()->GetPlayer();
+
+        if (enable.has_value())
+            player->SetGMSpectator(*enable);
+        else
+            player->SetGMSpectator(!player->IsGMSpectator());
+        handler->SendNotification(player->IsGMSpectator() ? LANG_GM_SPECTATOR_ON : LANG_GM_SPECTATOR_OFF);
+
+        return true;
+    }
 };
 
 void AddSC_gm_commandscript()