Add character screen model preview, item icons, stats panel, and fix targeting bugs

Enhanced the C-key character screen with a 3-column layout featuring a 3D
character model preview (with drag-to-rotate), item icons loaded from BLP
textures via ItemDisplayInfo.dbc, and a stats panel showing base + equipment
bonuses. Fixed selection circle clipping under terrain by adding a Z offset,
and corrected faction hostility logic that was wrongly marking hostile mobs
as friendly.

include/game/npc_manager.hpp

@@ -26,6 +26,8 @@ struct NpcSpawnDef {
     float rotation;          // radians around Z
     float scale;
     bool isCritter;          // critters don't do humanoid emotes
+    uint32_t faction = 0;    // faction template ID from creature_template
+    uint32_t npcFlags = 0;   // NPC interaction flags from creature_template
 };
 
 struct NpcInstance {