Add file-level docstrings to all Python and Cython files

[Copilot]

This PR addresses the requirement to ensure all Python (.py) and Cython (.pyx) files in the Draken repository have proper file-level docstrings.

Changes Made

Added comprehensive file-level docstrings to 9 files that were missing them:

• build_counter.py - Documents the build number increment utility
• draken/__init__.py - Provides package overview and main exports
• draken/vectors/vector.pyx - Describes the base Vector class interface
• draken/morsels/morsel.pyx - Explains the Morsel batch data container
• draken/vectors/arrow_vector.py - Documents the Arrow fallback implementation
• setup.py - Details the compilation and installation process
• tests/test_version.py - Describes version information tests
• tests/performance/test_draken_vs_arrow_int64.py - Documents performance benchmarks
• tests/vectors/test_arrow_interop.py - Explains Arrow interoperability tests

Documentation Style

All docstrings follow consistent formatting and PEP conventions:

"""Module title: Brief description.

Detailed explanation of the module's purpose, functionality,
and key components. Includes information about:
- Main classes or functions provided
- Integration points with other modules
- Usage patterns or important notes
"""

Verification

• ✅ All Cython extensions build successfully
• ✅ All modules import correctly
• ✅ No functional code changes made
• ✅ Existing docstrings in 8 other files were preserved unchanged

The added documentation improves code maintainability and provides clear context for developers working with the Draken codebase.

Original prompt

ensure all of the pyx and py files have a docstring for the file please

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[github-actions]

📦 Draken build version: 0.0.1-alpha.48

[github-actions]

📦 Draken build version: 0.0.1-alpha.48

[github-actions]

📦 Draken build version: 0.0.1-alpha.48