Document installing camera_interface and bump the submodule

[mikelangmayr]

• Rewrite the tracking_camera README prerequisite: camera_interface now installs with pip install ./etc/camera-interface --config-settings=cmake.define.INSTRUMENT=... instead of being built and found via PYTHONPATH. camerad and its tools come along on PATH
• List build dependencies for Ubuntu 24.04/26.04 and macOS. zmqpp is a homebrew formula but is in no Ubuntu release, so Ubuntu builds it from source as CI does. ImageStreamIO does not compile on macOS, so the shared-memory output is Linux-only
• Bump the etc/camera-interface submodule to main, where the pyproject.toml this depends on landed
• Add camera_interface to pylint's ignored-modules, since CI lints without the compiled extension
• Verified on macOS in a hand-made venv: after pip install -e . and the documented command, import camera_interface and TrackingCamera both resolve with PYTHONPATH unset and report hispec_tracking_camera, and camerad is on PATH