Sud._parse_data() already falls back to config.json's Pot section when
a loaded sud.json doesn't override 'mass', but neither client actually
passed that config through, so displayed pot mass silently read 0 kg
whenever a recipe didn't set its own 'pot.mass'.
client/brewpi_gui.py: capture the System message's 'Pot' key (already
sent by the server, previously ignored) into self.pot_config, and pass
it to Sud._parse_data(doc, self.pot_config).
web/app.js: parseSudDoc()'s potMass now falls back to the module-level
potConfig.mass (already captured from msg.Pot elsewhere, just never
consulted here) before defaulting to 0.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01M2ierBoxW3v7nUbDw3M2pE