Merge release/v1.42.0 with the day view into v142/t3-timeline

The timeline now opens a day through the shell's day layer (openDay) and reads ?day= with its parser instead of a copy of both; the capture picker's life-event form starts on the picker's defaultDate like the other forms.

src/__tests__/i18n-reverse-coverage.test.ts

@@ -79,7 +79,6 @@ const DYNAMIC_ALLOWLIST_PREFIXES = [
  */
 const RELEASE_PENDING_PREFIXES: Record<string, string> = {
   "labs.convertedFrom": "v1.42 lab unit conversion note (#1095)",
-  day: "v1.42 day view and its entry points (#613)",
 };
 
 /**