Server-side infrastructure for information asymmetry in dialogue.
NPCs display role labels (Worker, Supervisor, Patron) instead of
real names until the player explicitly learns them via KG lookup.
NpcColorIndex (stable_id % 8) persists across name reveal.
ConversationEvent and DialogueResponseEvent carry display names +
color indices on the wire with serde(default) for compat.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>