feat: migrate to reed-solomon-simd only implementation

- Remove reed-solomon-erasure dependency and all related code
- Simplify ReedSolomonEncoder from enum to struct with SIMD-only implementation
- Eliminate all conditional compilation (#[cfg(feature = ...)])
- Add instance caching with RwLock-based encoder/decoder reuse
- Implement reset mechanism to avoid unnecessary allocations
- Ensure thread safety with proper cache management
- Update documentation and benchmark scripts for SIMD-only approach
- Apply code formatting across all files

Breaking Changes:
- Removes support for reed-solomon-erasure feature flag
- API remains compatible but implementation is now SIMD-only

Performance Impact:
- Improved encoding/decoding performance through SIMD optimization
- Reduced memory allocations via instance caching
- Enhanced thread safety and concurrency support

ecstore/benches/comparison_benchmark.rs

@@ -12,7 +12,7 @@
 //! cargo bench --bench comparison_benchmark --features reed-solomon-simd
 //!
 //! # 测试强制 erasure-only 模式
-//! cargo bench --bench comparison_benchmark --features reed-solomon-erasure
+//! cargo bench --bench comparison_benchmark
 //!
 //! # 生成对比报告
 //! cargo bench --bench comparison_benchmark -- --save-baseline erasure

ecstore/benches/erasure_benchmark.rs

@@ -1,7 +1,7 @@
 //! Reed-Solomon erasure coding performance benchmarks.
 //!
 //! This benchmark compares the performance of different Reed-Solomon implementations:
-//! - Default (Pure erasure): Stable reed-solomon-erasure implementation
+//! - SIMD mode: High-performance reed-solomon-simd implementation
 //! - `reed-solomon-simd` feature: SIMD mode with optimized performance
 //!
 //! ## Running Benchmarks
@@ -235,7 +235,7 @@ fn bench_decode_performance(c: &mut Criterion) {
         group.finish();
 
         // 如果使用混合模式（默认），测试SIMD解码性能
-        #[cfg(not(feature = "reed-solomon-erasure"))]
+
         {
             let shard_size = calc_shard_size(config.data_size, config.data_shards);
             if shard_size >= 512 {