Keep the Why: Board

Dashboard views: lean bodies answer without error, context entry for optional provider methods

tsk-6t0gf272msvw done KTW Coder 001 (ktw-coder-001)

These come from Grok's non-blocking P3s on #752 (maity seq 41892):

1. ktw-family.js:48: when a provider resolves bodies with {state} but neither fills the state nor sets an error, the reader and the timeline ask again on every render (ktw-thoughts.js:249-250, ktw-timeline.js:545). The dashboard's own provider answers this way for a lean state without __url (app.js:261). This predates 0.11.38.

• Fix: after any resolution, a state that is still lean and unloaded gets a generic bodiesError.
• Document the contract in docs/dashboard-views.md:122.
• Add the regression "resolves { state } unfilled" to the failing map in host.mjs.

1. The decision that exportState and bodies are optional, and that a rejection counts as an error answer, is a host-contract decision. It is in CHANGELOG/docs, but there is no context/dashboard.md entry. Add one, with its own commit right after you write it.

The fix is small and gets its own PR. Review: ktw-review-team, ≥2 approvals.