重构：RustCrypto 兼容接口

主要变更：
- 新增 sm2/、sm3/、sm4/ 独立 crate，实现 RustCrypto traits
  - sm2：实现 signature、elliptic-curve traits
  - sm3：实现 digest、crypto-common traits
  - sm4：实现 cipher、aead traits
- 新增 fuzz/ 模糊测试目标
- 新增 tests/sm2_proptest.rs 属性测试
- 重构 src/sm4/ 使用 RustCrypto AEAD traits
- 更新 CI 工作流支持多 crate 测试
- 更新 .gitignore 忽略 fuzz/target/

benches/sm4_bench.rs

@@ -1,15 +1,14 @@
 use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion};
-use libsmx::sm4::{sm4_encrypt_ecb, Sm4Key};
+use libsmx::sm4::Sm4Key;
 
-fn bench_sm4_ecb(c: &mut Criterion) {
-    let mut group = c.benchmark_group("SM4-ECB");
+fn bench_sm4_block_encrypt(c: &mut Criterion) {
+    let mut group = c.benchmark_group("SM4-block");
     let key = [0u8; 16];
-    for size in [16usize, 1024, 65536] {
-        let data = vec![0u8; size];
-        group.bench_with_input(BenchmarkId::new("encrypt", size), &data, |b, d| {
-            b.iter(|| sm4_encrypt_ecb(&key, d));
-        });
-    }
+    let sm4 = Sm4Key::new(&key);
+    group.bench_function("encrypt_block", |b| {
+        let mut block = [0u8; 16];
+        b.iter(|| sm4.encrypt_block(&mut block));
+    });
     group.finish();
 }
 
@@ -20,5 +19,22 @@ fn bench_sm4_key_new(c: &mut Criterion) {
     });
 }
 
-criterion_group!(benches, bench_sm4_ecb, bench_sm4_key_new);
+fn bench_sm4_throughput(c: &mut Criterion) {
+    let mut group = c.benchmark_group("SM4-throughput");
+    let key = [0u8; 16];
+    let sm4 = Sm4Key::new(&key);
+    for size in [16usize, 1024, 65536] {
+        let mut data = vec![0u8; size];
+        group.bench_with_input(BenchmarkId::new("encrypt", size), &size, |b, _| {
+            b.iter(|| {
+                for chunk in data.chunks_exact_mut(16) {
+                    sm4.encrypt_block(chunk.try_into().unwrap());
+                }
+            });
+        });
+    }
+    group.finish();
+}
+
+criterion_group!(benches, bench_sm4_block_encrypt, bench_sm4_key_new, bench_sm4_throughput);
 criterion_main!(benches);