feat(profile): persist and expose the date-format preference

Accept dateFormat on the profile PATCH field-by-field, echo it from
the profile + /me reads, mirror it into the client auth user, and add
the field to the OpenAPI request/response schemas.

src/components/settings/__tests__/disable-coach-card.test.tsx

@@ -68,6 +68,7 @@ function buildUser(disableCoach: boolean): AuthUser {
     glucoseUnit: null,
     unitPreference: "metric",
     timeFormat: "AUTO",
+    dateFormat: "AUTO",
     disableCoach,
     fullName: null,
     insurerName: null,

src/components/settings/__tests__/modules-section.test.tsx

@@ -70,6 +70,7 @@ function buildUser(modules: AuthUser["modules"]): AuthUser {
     glucoseUnit: null,
     unitPreference: "metric",
     timeFormat: "AUTO",
+    dateFormat: "AUTO",
     disableCoach: false,
     fullName: null,
     insurerName: null,

src/components/settings/__tests__/time-format-select.test.tsx

@@ -46,6 +46,7 @@ function buildUser(timeFormat: TimeFormatPreference): AuthUser {
     glucoseUnit: null,
     unitPreference: "metric",
     timeFormat,
+    dateFormat: "AUTO",
     disableCoach: false,
     fullName: null,
     insurerName: null,

src/components/settings/__tests__/unit-preference-select.test.tsx

@@ -49,6 +49,7 @@ function buildUser(unitPreference: "metric" | "imperial"): AuthUser {
     glucoseUnit: null,
     unitPreference,
     timeFormat: "AUTO",
+    dateFormat: "AUTO",
     disableCoach: false,
     fullName: null,
     insurerName: null,