Python Resource Management

This handles Python resource cleanup the right way with proper context managers, both sync and async variants. You get patterns for database connections, file handles, streaming responses that accumulate state, and the tricky bits like selective exception suppression and nested resource cleanup. The examples show real __enter__/__exit__ implementations, not just the contextlib shortcuts. Covers the cases where resources absolutely must be released even when things go wrong, which is most production code involving databases, files, or network connections.