Add Tier 2 utility commands: helm/cloak toggles, follow, and assist

Display Toggle Commands:
- Add /helm, /helmet, /showhelm to toggle helm visibility
- Add /cloak, /showcloak to toggle cloak visibility
- Track visibility state with helmVisible_ and cloakVisible_ flags
- Show confirmation messages: "Helm/Cloak is now visible/hidden"
- Use CMSG_SHOWING_HELM (0x2B9) and CMSG_SHOWING_CLOAK (0x2BA)

Follow Command:
- Add /follow and /f to follow current target
- Works with both players and NPCs
- Show "Now following [Name]" confirmation message
- Track follow target with followTargetGuid_ for future movement logic

Assist Command:
- Add /assist to target what your current target is targeting
- Read target's target from UNIT_FIELD_TARGET update fields (offset 6-7)
- Reconstruct 64-bit target GUID from two 32-bit field values
- Automatically switch your target to assist target
- Show helpful messages: "[Name] has no target" when appropriate
- Essential for combat coordination in groups

Implementation:
- Add ShowingHelmPacket and ShowingCloakPacket builders
- Add toggleHelm() and toggleCloak() methods with state management
- Add followTarget() for setting follow target
- Add assistTarget() with smart target field reading
- Use Entity::getFields() to access protected update fields
- Handle missing targets and invalid states gracefully
- All commands provide chat feedback
- Support multiple aliases for user convenience

src/ui/game_screen.cpp

@@ -1150,6 +1150,34 @@ void GameScreen::sendChatMessage(game::GameHandler& gameHandler) {
                 return;
             }
 
+            // /helm command
+            if (cmdLower == "helm" || cmdLower == "helmet" || cmdLower == "showhelm") {
+                gameHandler.toggleHelm();
+                chatInputBuffer[0] = '\0';
+                return;
+            }
+
+            // /cloak command
+            if (cmdLower == "cloak" || cmdLower == "showcloak") {
+                gameHandler.toggleCloak();
+                chatInputBuffer[0] = '\0';
+                return;
+            }
+
+            // /follow command
+            if (cmdLower == "follow" || cmdLower == "f") {
+                gameHandler.followTarget();
+                chatInputBuffer[0] = '\0';
+                return;
+            }
+
+            // /assist command
+            if (cmdLower == "assist") {
+                gameHandler.assistTarget();
+                chatInputBuffer[0] = '\0';
+                return;
+            }
+
             // Chat channel slash commands
             bool isChannelCommand = false;
             if (cmdLower == "s" || cmdLower == "say") {