app.py's dev server and gunicorn both hardcoded 5000, which is awkward
locally — macOS ControlCenter already holds that port, so the app can't
bind on the dev laptop without editing source.
Both now read PORT, defaulting to 5000 so EXPOSE, the compose
`${HOST_PORT}:5000` mapping and the deployed container are unchanged.
Read at run time rather than import time so a dev harness can assign a
free port.
Also tracks .claude/launch.json with autoPort set. It doesn't actually
launch on this machine — the preview sandbox can't read files under
~/Desktop — so CLAUDE.md notes that running from a shell with an
explicit PORT is the working local path.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
