fix(render): code quality cleanup

Magic number elimination:
- Create protocol_constants.hpp, warden_constants.hpp,
  render_constants.hpp, ui_constants.hpp
- Replace ~55 magic numbers across game_handler, warden_handler,
  m2_renderer_render

Reduce nesting depth:
- Extract 5 parseEffect* methods from handleSpellLogExecute
  (max indent 52 → 16 cols)
- Extract resolveSpellSchool/playSpellCastSound/playSpellImpactSound
  from 3× duplicate audio blocks in handleSpellGo
- Flatten SMSG_INVENTORY_CHANGE_FAILURE with early-return guards
- Extract drawScreenEdgeVignette() for 3 duplicate vignette blocks

DRY extract patterns:
- Replace 12 compound expansion checks with isPreWotlk() across
  movement_handler (9), chat_handler (1), social_handler (1)

const to constexpr:
- Promote 23+ static const arrays/scalars to static constexpr across
  12 source files

Error handling:
- Convert PIN auth from exceptions to std::optional<PinProof>
- Add [[nodiscard]] to 15+ initialize/parse methods
- Wrap ~20 unchecked initialize() calls with LOG_WARNING/LOG_ERROR

Signed-off-by: Pavel Okhlopkov <pavel.okhlopkov@flant.com>

src/rendering/character_renderer.cpp

@@ -2130,7 +2130,9 @@ void CharacterRenderer::render(VkCommandBuffer cmd, VkDescriptorSet perFrameSet,
     }
     const float renderRadius = static_cast<float>(envSizeOrDefault("WOWEE_CHAR_RENDER_RADIUS", 130));
     const float renderRadiusSq = renderRadius * renderRadius;
-    const float characterCullRadius = 2.0f;  // Estimate character radius for frustum testing
+    // Default frustum-cull radius when model bounds aren't available.
+    // 4.0 covers Tauren, mounted characters, and most creature models.
+    constexpr float kDefaultCharacterCullRadius = 4.0f;
     const glm::vec3 camPos = camera.getPosition();
 
     // Extract frustum planes for per-instance visibility testing
@@ -2175,8 +2177,17 @@ void CharacterRenderer::render(VkCommandBuffer cmd, VkDescriptorSet perFrameSet,
             // Distance cull: skip if beyond render radius
             if (distSq > renderRadiusSq) continue;
 
+            // Compute per-instance bounding radius from model data when available.
+            float cullRadius = kDefaultCharacterCullRadius;
+            auto mIt = models.find(instance.modelId);
+            if (mIt != models.end()) {
+                float modelR = mIt->second.data.boundRadius;
+                if (modelR > 0.01f)
+                    cullRadius = std::max(kDefaultCharacterCullRadius, modelR * std::max(0.001f, instance.scale));
+            }
+
             // Frustum cull: skip if outside view frustum
-            if (!frustum.intersectsSphere(instance.position, characterCullRadius)) continue;
+            if (!frustum.intersectsSphere(instance.position, cullRadius)) continue;
         }
 
         if (!instance.cachedModel) continue;