feat(organise): implement project file organization based on manifest

[ZeroSumQuant]

Summary

• Implements Phase-4 Task B: Project organizer that moves files based on manifest classifications
• Adds comprehensive test suite with 14 tests covering all scenarios
• Works in both dry-run mode (planning) and apply mode (execution)

Implementation Details

• _target_path_for_file(): Determines target directory based on file classification
• organise_project(): Executes file moves using git mv (when available) or shutil.move
• Automatically creates init.py files and data/README.md as needed
• Idempotent: running twice produces no changes
• Skips files that already exist at target location

Test Coverage

• Target path calculation for all file types
• Dry-run mode operation
• Git-less operation (skip_git=True)
• Handling of existing target files
• Automatic creation of support files
• Idempotency verification

🤖 Generated with Claude Code