feat: Add --no-prefix option to disable hostname prefix in output (pdsh -N compatibility)

[inureyes]

Summary

• Add --no-prefix / -N option that disables hostname prefix in output lines
• Provides pdsh compatibility for the -N flag
• Works in stream mode (--stream) and file output mode (--output-dir)
• Useful for programmatic parsing or cleaner display

Changes

Implementation

• Add --no-prefix / -N option to CLI struct in src/cli.rs
• Add no_prefix field to ExecuteCommandParams
• Modify OutputMode to track no_prefix setting for Stream and File modes
• Update NodeOutputWriter to conditionally format output with/without prefix
• Thread no_prefix option through ParallelExecutor streaming handlers

Tests

• Add unit tests for no_prefix functionality in output_sync.rs and output_mode.rs
• Add CLI parsing tests for --no-prefix/-N option (10 test cases) in tests/no_prefix_test.rs

Documentation

• Update README.md with --no-prefix in Command-Line Options section
• Update README.md Stream Mode section with --no-prefix usage example
• Update manpage (bssh.1) with --no-prefix/-N option documentation

Usage

# Default behavior (with prefix)
bssh -H "node1,node2" "uname -a"
# Output:
# [node1] Linux node1 5.15.0
# [node2] Linux node2 5.15.0

# With --no-prefix
bssh -H "node1,node2" --no-prefix "uname -a"
# Output:
# Linux node1 5.15.0
# Linux node2 5.15.0

# With --stream mode
bssh -C production --stream --no-prefix "tail -f /var/log/syslog"

Test plan

• Build passes without errors
• All existing tests pass (232+ tests)
• New unit tests added for no_prefix functionality
• New CLI parsing tests added (10 test cases)
• --help shows the new option correctly
• README.md updated with option documentation
• Manpage updated with option documentation

Closes #92