Give labels a color (migration 0011 adds labels.color, server_default 'default' so existing labels keep the neutral chip). The PATCH endpoint now updates name and/or color; note serialization carries each label's color. Frontend: a swatch picker per label in the Edit-labels modal, colored chips on cards + in the editor (LABEL_CHIP_CLASSES), and a color dot on each sidebar label. Reuses the note color vocabulary. (Graph node coloring rides this in the graph-liveliness task.) Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01FRgehjoz7Yv8LkUfADxACm