feat: 实现多个挑战并改进测试

- 重写p1实现纯Rust的hex到base64转换
- 完成p13 ECB剪切粘贴攻击和破解脚本
- 实现p33 Diffie-Hellman密钥交换算法
- 修复p9的PKCS#7测试用例
- 在common库添加gen_random_key和pkcs7_unpadding函数
- 更新workspace依赖管理

problems/p33/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "p33"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+num-bigint = { workspace = true }
+num-traits = { workspace = true }
+rand = { workspace = true }
+anyhow = { workspace = true }
+once_cell = { workspace = true }