Mirrors /api/dashboard/widgets for the insights surface: GET returns
the user's saved layout (defaulting to project order when unset),
PUT writes the layout, the response is the canonical shape the
clients can render directly. Closes the cross-device drift where
insights ordering lived in iOS local state only.
Storage is a new `insights_layout_json` JSONB column on `users`,
parallel to `dashboard_widgets_json` so each surface's resolver owns
its tile-id allowlist. Migration 0083 adds the column idempotently;
default NULL resolves to `DEFAULT_INSIGHTS_LAYOUT`. PUT routes
through the shared multi-issue 422 envelope + payload-redaction +
audit-row dedup pattern the dashboard-widgets route established.
A 5-minute per-user cache mirrors the dashboard-widgets cache and
busts on every save / reset.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
