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/m2_renderer.hpp

@@ -76,6 +76,8 @@ struct M2ModelGPU {
     bool isSmallFoliage = false;  // Small foliage (bushes, grass, plants) - skip during taxi
     bool isInvisibleTrap = false; // Invisible trap objects (don't render, no collision)
     bool isGroundDetail = false;  // Ground clutter/detail doodads (special fallback render path)
+    bool isWaterVegetation = false; // Cattails, reeds, kelp etc. near water (insect spawning)
+    bool isFireflyEffect = false;   // Firefly/fireflies M2 (exempt from particle dampeners)
 
     // Collision mesh with spatial grid (from M2 bounding geometry)
     struct CollisionMesh {
@@ -307,6 +309,8 @@ public:
     void setInsideInterior(bool inside) { insideInterior = inside; }
     void setOnTaxi(bool onTaxi) { onTaxi_ = onTaxi; }
 
+    std::vector<glm::vec3> getWaterVegetationPositions(const glm::vec3& camPos, float maxDist) const;
+
 private:
     bool initialized_ = false;
     bool insideInterior = false;