refactor: remove unwrap calls, propagate errors, and fix logging levels

[Himess]

Summary

This pull request addresses several TODOs across different modules by improving error handling and logging consistency.

sns-worker/src/executor.rs

• Removed unwrap() from decompress_ct call.
• Added proper error propagation and tracing span completion to prevent panic during ciphertext decompression.

kms-connector/src/core/decryption/handler.rs

• Adjusted ciphertext logging level from info! to debug!.
• Cleaned up redundant comments and aligned with intended TODO (“revert to DEBUG”).

host-listener/src/cmd/mod.rs

• Replaced a panic! in new_log_stream() with graceful error propagation via anyhow::Result.
• Updated function signature and all call sites to properly handle the returned Result.

These changes remove unsafe panic and unwrap calls, ensure consistent logging levels, and make error handling across the FHEVM engine modules more robust and maintainable.