Make the listen port configurable via PORT

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>

app.py

@@ -1543,4 +1543,8 @@ def add_to_sonarr():
 
 
 if __name__ == "__main__":
-    app.run(host="0.0.0.0", port=5000)
+    # PORT is read at run time, not import time, so a dev harness can hand us
+    # a free port. Defaults to 5000 to match EXPOSE/gunicorn and the
+    # `${HOST_PORT}:5000` mapping in docker-compose.yml — don't change the
+    # default without changing all three.
+    app.run(host="0.0.0.0", port=int(os.environ.get("PORT", "5000")))