feat: add guild management (invite, kick, promote, demote, leave, notes)

GuildInvite(name) invites a player to the guild.
GuildUninvite(name) kicks a member (uses kickGuildMember).
GuildPromote(name) / GuildDemote(name) change rank.
GuildLeave() leaves the guild.
GuildSetPublicNote(name, note) sets a member's public note.

All backed by existing GameHandler methods that send the appropriate
guild management CMSG packets.

src/addons/lua_engine.cpp

@@ -5182,6 +5182,37 @@ void LuaEngine::registerCoreAPI() {
             if (gh) gh->requestPvpLog();
             return 0;
         }},
+        // --- Guild Management ---
+        {"GuildInvite", [](lua_State* L) -> int {
+            auto* gh = getGameHandler(L);
+            if (gh) gh->inviteToGuild(luaL_checkstring(L, 1));
+            return 0;
+        }},
+        {"GuildUninvite", [](lua_State* L) -> int {
+            auto* gh = getGameHandler(L);
+            if (gh) gh->kickGuildMember(luaL_checkstring(L, 1));
+            return 0;
+        }},
+        {"GuildPromote", [](lua_State* L) -> int {
+            auto* gh = getGameHandler(L);
+            if (gh) gh->promoteGuildMember(luaL_checkstring(L, 1));
+            return 0;
+        }},
+        {"GuildDemote", [](lua_State* L) -> int {
+            auto* gh = getGameHandler(L);
+            if (gh) gh->demoteGuildMember(luaL_checkstring(L, 1));
+            return 0;
+        }},
+        {"GuildLeave", [](lua_State* L) -> int {
+            auto* gh = getGameHandler(L);
+            if (gh) gh->leaveGuild();
+            return 0;
+        }},
+        {"GuildSetPublicNote", [](lua_State* L) -> int {
+            auto* gh = getGameHandler(L);
+            if (gh) gh->setGuildPublicNote(luaL_checkstring(L, 1), luaL_checkstring(L, 2));
+            return 0;
+        }},
         // --- Emotes ---
         {"DoEmote", [](lua_State* L) -> int {
             auto* gh = getGameHandler(L);