* storage: fix EC shard recovery with improved diagnostics and logging
- Fix buffer size mismatch in ReconstructData call
- Add detailed logging of available and missing shards
- Improve error messages when recovery is impossible
- Add unit tests for EC recovery shard counting logic
* test: refine EC recovery unit tests
- Remove redundant tests that only validate setup
- Use standard strings.Contains instead of custom recursive helper
* adjust tests and minor improvement
