refactor: 项目目录结构重组

- 中文目录名改为英文：cDNA图像处理实例→examples，参考资料→references
- web→app（Flask应用标准命名）
- 输出目录平移到 data/output/simple/ 和 data/output/full/
- 输入图像统一到 data/input/
- 构建脚本移到 scripts/
- 源码文件改用 snake_case 命名
- 更新所有文件路径引用和文档

references/matlab/Heaviside.m

@@ -0,0 +1,14 @@
+function H=Heaviside(z)
+% Heaviside step function (smoothed version)
+% Copyright (c) 2009, 
+% Yue Wu @ ECE Department, Tufts University
+% All Rights Reserved  
+
+Epsilon=10^(-5);
+H=zeros(size(z,1),size(z,2));
+idx1=find(z>Epsilon);
+idx2=find(z<Epsilon & z>-Epsilon);
+H(idx1)=1;
+for i=1:length(idx2)
+    H(idx2(i))=1/2*(1+z(idx2(i))/Epsilon+1/pi*sin(pi*z(idx2(i))/Epsilon));
+end;