feat: journal dashboard widgets, agent polish, and edit-mode live previews

Journal dashboard widgets and quick-add; rich-text quick-add dialogs.

Dashboard draft sync for live edit previews; assistant bubble + API tools.

Journal UX: stress slider, mood grid, query cap fix.

src/modules/journal/day-key.ts

@@ -8,3 +8,20 @@ export function toDayKey(date: Date): string {
 export function recordedDayKey(iso: string): string {
   return toDayKey(new Date(iso));
 }
+
+export function dayKeyToMonthStart(dayKey: string): Date | null {
+  const match = /^(\d{4})-(\d{2})-(\d{2})$/.exec(dayKey);
+  if (!match) return null;
+  return new Date(Number(match[1]), Number(match[2]) - 1, 1);
+}
+
+export function formatDayKeyLabel(dayKey: string): string {
+  const match = /^(\d{4})-(\d{2})-(\d{2})$/.exec(dayKey);
+  if (!match) return dayKey;
+  const date = new Date(Number(match[1]), Number(match[2]) - 1, Number(match[3]));
+  return date.toLocaleDateString(undefined, { month: "long", day: "numeric", year: "numeric" });
+}
+
+export function buildEntryDaySet(entries: Array<{ recordedAt: string }>): Set<string> {
+  return new Set(entries.map((entry) => recordedDayKey(entry.recordedAt)));
+}