Add ambient insect particles near water vegetation, fix firefly particles, and improve water foam

- Spawn dark point-sprite insects buzzing around cattails/reeds/kelp/seaweed
- Fix firefly M2 particles: exempt from alpha dampening and forced gravity
- Make water shoreline/crest foam more irregular with UV warping and bluer tint

include/rendering/swim_effects.hpp

@@ -11,6 +11,7 @@ namespace rendering {
 class Camera;
 class CameraController;
 class WaterRenderer;
+class M2Renderer;
 class VkContext;
 
 class SwimEffects {
@@ -25,6 +26,7 @@ public:
                 const WaterRenderer& water, float deltaTime);
     void render(VkCommandBuffer cmd, VkDescriptorSet perFrameSet);
     void spawnFootSplash(const glm::vec3& footPos, float waterH);
+    void setM2Renderer(M2Renderer* renderer) { m2Renderer = renderer; }
 
 private:
     struct Particle {
@@ -36,14 +38,30 @@ private:
         float alpha;
     };
 
+    struct InsectParticle {
+        glm::vec3 position;
+        glm::vec3 orbitCenter;  // vegetation position to orbit around
+        float lifetime;
+        float maxLifetime;
+        float size;
+        float alpha;
+        float phase;       // random phase offset for erratic motion
+        float orbitRadius;
+        float orbitSpeed;
+        float heightOffset; // height above plant
+    };
+
     static constexpr int MAX_RIPPLE_PARTICLES = 200;
     static constexpr int MAX_BUBBLE_PARTICLES = 150;
+    static constexpr int MAX_INSECT_PARTICLES = 50;
 
     std::vector<Particle> ripples;
     std::vector<Particle> bubbles;
+    std::vector<InsectParticle> insects;
 
     // Vulkan objects
     VkContext* vkCtx = nullptr;
+    M2Renderer* m2Renderer = nullptr;
 
     // Ripple pipeline + dynamic buffer
     VkPipeline ripplePipeline = VK_NULL_HANDLE;
@@ -61,14 +79,25 @@ private:
     VmaAllocationInfo bubbleDynamicVBAllocInfo{};
     VkDeviceSize bubbleDynamicVBSize = 0;
 
+    // Insect pipeline + dynamic buffer
+    VkPipeline insectPipeline = VK_NULL_HANDLE;
+    VkPipelineLayout insectPipelineLayout = VK_NULL_HANDLE;
+    ::VkBuffer insectDynamicVB = VK_NULL_HANDLE;
+    VmaAllocation insectDynamicVBAlloc = VK_NULL_HANDLE;
+    VmaAllocationInfo insectDynamicVBAllocInfo{};
+    VkDeviceSize insectDynamicVBSize = 0;
+
     std::vector<float> rippleVertexData;
     std::vector<float> bubbleVertexData;
+    std::vector<float> insectVertexData;
 
     float rippleSpawnAccum = 0.0f;
     float bubbleSpawnAccum = 0.0f;
+    float insectSpawnAccum = 0.0f;
 
     void spawnRipple(const glm::vec3& pos, const glm::vec3& moveDir, float waterH);
     void spawnBubble(const glm::vec3& pos, float waterH);
+    void spawnInsect(const glm::vec3& vegPos);
 };
 
 } // namespace rendering