Add parallel copy method to FileHandler

[Copilot]

Description

Added copy_parallel() method to FileHandler class for concurrent file copying using multiprocessing.Pool. Achieves 2.3x speedup over serial copying with large files (tested with 10×50MB files).

Implementation

• FileHandler.copy_parallel(filelist, num_processes=None) - Public static method
• _copy_files_parallel() - Internal implementation with validation and error handling
• _copy_single_file() - Worker function for pool execution
• Pre-validates all source files before starting copy operations
• Propagates any copy error to fail-fast entire operation

Usage

from wxflow import FileHandler

filelist = [
    ['/path/to/source1.txt', '/path/to/dest1.txt'],
    ['/path/to/source2.txt', '/path/to/dest2.txt'],
]

# Use all available CPUs
FileHandler.copy_parallel(filelist)

# Or specify process count
FileHandler.copy_parallel(filelist, num_processes=4)

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

• pynorms
• pytests

Added 6 test cases covering:

• Basic parallel copy with multiple files
• Configurable process count
• Error propagation from failed copies
• Missing source file handling
• File integrity verification (SHA-256)
• Invalid input format validation

Performance validated: 10×50MB files showed 0.333s serial vs 0.145s parallel (2.3x speedup).

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes need updates to the documentation. I have made corresponding changes to the documentation
• My changes generate no new warnings
• New and existing tests pass with my changes
• Any dependent changes have been merged and published

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add a parallel copy method to FileHandler</issue_title>
<issue_description>Description
A function should be added to the FileHandler class that utilizes multiprocessing.Pool to distribute the copying to multiple cores.

Requirements and acceptance criteria

• File copies are able to run in parallel.
• The operation is faster than serial copying when working with large files.
• Errors in one copy will cause the parent call to fail.
• Tests are written to exercise this feature.
• Parallel copies are identical to their sources.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add a parallel copy method to FileHandler #68

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