feat: water effects (#19)

* feat(shaders): add lighting to block accumulation OIT shaders

* feat(renderer): add water rendering with OIT and new shaders

* feat(water): implement screen-space reflection and refraction for water with depth fade and perturbation

* refactor(shader): replace glUniform calls with generic set_loc and remove cached locations

* feat(water): add noise-based caustics and configurable fog density

* fix(water shader): update depth fade and remove underwater check

- Increase DEPTH_FADE_DISTANCE from 8 to 10
- Remove conditional so depth fade always applies
- Darken deepColor from (0, 0.08, 0.15) to (0, 0.015, 0.045)

* feat(underwater): add volume scattering and shadow mapping for light shafts

assets/shaders/water_v_shader.glsl

@@ -0,0 +1,32 @@
+#version 460
+
+layout (location = 0) in vec3 pos;
+layout (location = 1) in vec2 texCoord;
+layout (location = 2) in float layer;
+layout (location = 3) in vec3 aNormal;
+layout (location = 4) in float Roughness;
+
+out vec2 tc;
+out vec3 normal;
+out vec3 vert_pos;
+out vec3 world_pos;
+flat out int tex_layer;
+out float roughness;
+out float v_depth;
+
+uniform mat4 mv_matrix;
+uniform mat4 proj_matrix;
+uniform mat4 norm_matrix;
+
+
+void main(void) {
+    vec4 view_pos = mv_matrix * vec4(pos, 1.0);
+    world_pos = pos;
+    vert_pos = view_pos.xyz;
+    normal = mat3(norm_matrix) * aNormal;
+    roughness = Roughness;
+    tc = texCoord;
+    tex_layer = int(layer);
+    v_depth = -view_pos.z;
+    gl_Position = proj_matrix * view_pos;
+}