build: Add Cython compilation support for wheel obfuscation

[devin-ai-integration]

Summary

Add Cython compilation to the PyAirbyte build pipeline so that PyPI-published wheels contain compiled .so/.pyd extensions instead of readable .py source files, providing basic code obfuscation for distribution from the private repo.

Context

This pattern has been prototyped in the airbyte-ops-mcp and connector-builder-mcp repos:

• Ops MCP PR: https://github.com/airbytehq/airbyte-ops-mcp/pull/343
• Connector Builder MCP PR: https://github.com/airbytehq/connector-builder-mcp/pull/208
• Related ops-mcp issue: https://github.com/airbytehq/airbyte-ops-mcp/issues/346

The approach uses:

• hatch-cythonize build hook (maintained fork of hatch-cython) to compile .py → .c → .so during wheel builds
• Build-time injection of Cython config (not stored in pyproject.toml) to avoid breaking uv sync / editable installs
• Post-build source stripping to remove .py files from wheels where compiled .so counterparts exist
• Exclusion of modules that break under Cython compilation (e.g., MCP/Pydantic presentation layers)

Key Learnings from Ops MCP Implementation

1. Cython config must NOT be in pyproject.toml — it runs during editable installs (uv sync), breaking CI workflows. Solution: inject at build time via a script.
2. Pydantic/FastMCP modules must be excluded — Cython-compiled functions (cyfunction) don't expose type annotations the same way, breaking Pydantic schema generation.
3. __init__.py files must be excluded — required for Python package structure.
4. Platform-specific wheels — must build per OS (Linux, macOS) and Python version (3.10, 3.11, 3.12).

Action Items

• Evaluate whether this pattern should be applied to PyAirbyte
• If yes, adapt the enable_cython_build.py and strip_source_from_wheel.py scripts for PyAirbyte's package structure
• Identify which modules (if any) need to be excluded from compilation
• Integrate with existing publish/release workflows

Devin session: https://app.devin.ai/sessions/7c8622f9452141d1bbad93f74079278f
Requested by: Aaron ("AJ") Steers (@aaronsteers)