feat: world-space floating combat text above entities

Combat text (damage, heals, misses, crits, etc.) now floats above the
target entity in 3D space instead of appearing at fixed screen positions.
Text rises upward from the entity's head, with random horizontal stagger
to prevent stacking. HUD-only types (XP, Honor, Procs) and entries
without a valid entity anchor fall back to the original screen overlay.

src/game/game_handler.cpp

@@ -15560,6 +15560,12 @@ void GameHandler::addCombatText(CombatTextEntry::Type type, int32_t amount, uint
     entry.age = 0.0f;
     entry.isPlayerSource = isPlayerSource;
     entry.powerType = powerType;
+    entry.srcGuid = srcGuid;
+    entry.dstGuid = dstGuid;
+    // Random horizontal stagger so simultaneous hits don't stack vertically
+    static std::mt19937 rng(std::random_device{}());
+    std::uniform_real_distribution<float> dist(-1.0f, 1.0f);
+    entry.xSeed = dist(rng);
     combatText.push_back(entry);
 
     // Persistent combat log — use explicit GUIDs if provided, else fall back to