feat(engagement): localize limits and streaks

Use reported user timezones for daily response limits, expose couple streak state and reminders, and improve swipe and live-drawing synchronization with focused tests and documentation.

apps/api/src/domains/profile-settings/repository.ts

@@ -16,6 +16,7 @@ interface PreferencesRow extends QueryResultRow {
   pack_changes_enabled: boolean;
   new_packs_enabled: boolean;
   streak_milestones_enabled: boolean;
+  streak_reminders_enabled: boolean;
   weekly_summary_enabled: boolean;
   unpaired_reminders_enabled: boolean;
   catchup_reminders_enabled: boolean;
@@ -49,6 +50,7 @@ const profileColumns: Record<keyof ProfileUpdate, string> = {
   onboarding_version: 'onboarding_version',
   public_key_jwk: 'public_key_jwk',
   push_token: 'push_token',
+  timezone: 'timezone',
 };
 
 function toPreferences(row: PreferencesRow): NotificationPreferences {
@@ -61,6 +63,7 @@ function toPreferences(row: PreferencesRow): NotificationPreferences {
     pack_changes_enabled: row.pack_changes_enabled,
     new_packs_enabled: row.new_packs_enabled,
     streak_milestones_enabled: row.streak_milestones_enabled,
+    streak_reminders_enabled: row.streak_reminders_enabled,
     weekly_summary_enabled: row.weekly_summary_enabled,
     unpaired_reminders_enabled: row.unpaired_reminders_enabled,
     catchup_reminders_enabled: row.catchup_reminders_enabled,

apps/api/src/domains/profile-settings/routes.ts

@@ -18,6 +18,8 @@ const profileUpdateSchema = z.object({
   onboarding_version: z.number().int().min(0).optional(),
   public_key_jwk: z.record(z.unknown()).nullable().optional(),
   push_token: z.string().trim().min(1).max(512).nullable().optional(),
+  // IANA zone from the client; the daily response limit buckets on the user's local day.
+  timezone: z.string().trim().min(1).max(64).nullable().optional(),
 }).strict().refine((body) => Object.keys(body).length > 0, 'At least one profile field is required');
 
 const preferenceSchema = z.object({

apps/api/src/domains/profile-settings/types.ts

@@ -6,6 +6,7 @@ export const notificationPreferenceKeys = [
   'pack_changes_enabled',
   'new_packs_enabled',
   'streak_milestones_enabled',
+  'streak_reminders_enabled',
   'weekly_summary_enabled',
   'unpaired_reminders_enabled',
   'catchup_reminders_enabled',
@@ -30,6 +31,7 @@ export interface ProfileUpdate {
   onboarding_version?: number;
   public_key_jwk?: Record<string, unknown> | null;
   push_token?: string | null;
+  timezone?: string | null;
 }
 
 export interface FeedbackSubmission {