Add batch processing support for processing multiple files

[chanshing]

Summary

Add comprehensive batch processing functionality to process multiple accelerometer files from a folder in a single command. This enables efficient processing of large datasets without manual scripting.

Key Features

• Batch folder processing: Process all matching files in a directory
• Smart file discovery: Filter by extension with --fileExtensions (required)
• Recursive search: Optional --recursive flag for subdirectory traversal
• Compression aware: Automatically matches .gz, .zip, .bz2, .xz variants
• Error isolation: Individual file failures don't stop batch processing
• Comprehensive reporting: Detailed summary with success/failure counts and timings
• Data protection: Detects duplicate basenames to prevent output overwrites
• Proper exit codes: Non-zero codes for CI/CD integration
• Backward compatible: Single file mode unchanged

Changes

src/accelerometer/accProcess.py

• Add matchesExtension() for file extension matching with compression support
• Add discoverFiles() for file discovery with recursive option
• Add processSingleFile() extracted from main() for reusability
• Add processBatch() to orchestrate batch processing
• Add --fileExtensions argument (required for batch mode)
• Add --recursive argument for subdirectory search
• Refactor main() to detect and route file vs directory input
• Implement try-finally cleanup for intermediate files
• Catch SystemExit to prevent device.py from killing batch
• Detect duplicate basenames and exit with clear error
• Exit with proper codes: 255 for setup errors, 1 for failures
• Respect --verbose flag in batch error reporting

README.md

• Add batch processing usage section with examples
• Update output paths to reflect outputs/{filename}/ structure
• Document new CLI arguments
• Explain compression format auto-detection

Usage Examples

# Process all CWA files in a folder
accProcess data/accelerometer_files/ --fileExtensions cwa

# Process multiple formats
accProcess data/ --fileExtensions cwa,bin,csv

# Recursive search
accProcess data/ --fileExtensions cwa --recursive True

# Single file (unchanged)
accProcess data/sample.cwa.gz

Testing

• ✅ Single file processing (backward compatibility)
• ✅ Batch processing with multiple files
• ✅ Extension filtering (single and multiple)
• ✅ Recursive vs non-recursive search
• ✅ Empty/malformed extensions handling
• ✅ Duplicate basename detection
• ✅ Error handling and exit codes
• ✅ Cleanup on exception
• ✅ SystemExit catching (from device.py)
• ✅ Flake8 compliance
• ✅ Code compilation

Exit Codes

• 0: Success (all files processed successfully)
• 1: Partial/complete failure (at least one file failed)
• 255: Setup error (no files found, duplicates, invalid arguments)

Breaking Changes

None. Single file processing remains unchanged. Batch mode is opt-in via directory input.