fix: use parallel config value from configuration file (#26)

* fix: use parallel config value from configuration file

Previously, the parallel setting in config files was completely ignored.
This fix implements proper config support for the parallel option:

- Add get_parallel() method to Config struct (follows same pattern as get_timeout)
- Add parallel field to ClusterDefaults struct
- Check if user explicitly specified -p/--parallel in CLI args
- Use config value when CLI option not explicitly provided
- Priority: CLI (if explicit) > Cluster config > Global defaults > CLI default (10)

Now users can set parallel in their config files:
  defaults:
    parallel: 50
  clusters:
    production:
      parallel: 100

Fixes the issue where config parallel values were defined but never used.

* chore: prepare release v0.5.4

* update: help documents (#19)

Author: inureyes

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "bssh"
-version = "0.5.3"
+version = "0.5.4"
 authors = ["Jeongkyu Shin <inureyes@gmail.com>"]
 description = "Parallel SSH command execution tool for cluster management"
 license = "Apache-2.0"

Cargo.toml

@@ -545,6 +545,7 @@ See the [LICENSE](./LICENSE) file for details.
 ## Changelog
 
 ### Recent Updates
+- **v0.5.4 (2025/08/27):** Fix parallel config value handling and align interactive mode authentication with exec mode
 - **v0.5.3 (2025/08/27):** Use Backend.AI cluster SSH key for auto-detected environments
 - **v0.5.2 (2025/08/27):** Fix config file loading priority, improve BACKENDAI environment handling, use cluster SSH key config
 - **v0.5.1 (2025/08/25):** Add configurable command timeout with support for unlimited execution (timeout=0), configurable via CLI and config file