Craft Graph

Documents "why it's this way" and "where the gotchas are" as a navigable graph. Each node is one decision/invariant/gotcha with a `file:line` proof. Use this skill whenever the user asks to record architectural decisions, rationale, or gotchas as a graph — "build a decision graph", "document the architecture as a graph", "a graph of gotchas/traps", "the project's decision map", "capture why it was done this way", "document the gotchas" — even without the words "graph" or "skill". Also trigger on onboarding a project into the discipline — "adopt craftlight", "seed the graph over the legacy", "onboard this project into craftlight". Not for "how does this work / business-log…