Add a "Compare to" pulldown to the Settings → Dashboard section that
lets the user pick None / Last month / Last year. The preference rides
on the existing User.dashboardWidgetsJson blob — research §7 Q3 settled
on the JSON-pivot path so v1.4.16 ships migration-free.
The resolver defaults to "none" for legacy layouts and clamps unknown
values back to "none", so a stale client cannot poison the dashboard
with a baseline the renderer doesn't know how to draw. The PUT
endpoint accepts the new optional comparisonBaseline field; pre-B8
clients keep PUTing without it and see no behavioural change.
EN+DE i18n keys land for the toggle label, the three options, the
"unavailable" fallback, and the chart caption — Vormonat / Vorjahr per
Marc's brief.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
