Create the foundational project structure for the zamenyat HTTP content replacement bridge, including a Makefile with targets for environment setup, installation, formatting, and building; a pyproject.toml declaring setuptools as the build backend; a setup.cfg with package metadata, dependencies on the internal app library, and a console_scripts entry point; a README.md with a corrected heading and project description; a __main__.py module implementing argument parsing for host, port, upstream-host, and upstream-port; and an app.py module defining the Application class with async header parsing, connection tracking, and configurable buffer/header size constants.
