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

include/game/world_packets.hpp

@@ -786,6 +786,22 @@ public:
     static network::Packet build(uint8_t state);
 };
 
+// ============================================================
+// Display Toggles
+// ============================================================
+
+/** CMSG_SHOWING_HELM packet builder */
+class ShowingHelmPacket {
+public:
+    static network::Packet build(bool show);
+};
+
+/** CMSG_SHOWING_CLOAK packet builder */
+class ShowingCloakPacket {
+public:
+    static network::Packet build(bool show);
+};
+
 // ============================================================
 // Random Roll
 // ============================================================