feat: add 14 new smart folder categories (locale-agnostic)

New EmailCategory enum values: Travel, Subscriptions, Parcels,
Recruitment, Events, SecurityAlerts, Healthcare, Education,
NewsMedia, PropertyUtilities, Charity, Government, CryptoInvesting,
FamilySchool.

HeuristicClassifier: locale-agnostic rules using global brand
domains + TLD patterns (.gov.*, .edu, .ac.*) + English subject
keywords — works for international users without relying on
country-specific domains (e.g. gov.uk).

Priority order ensures SecurityAlerts and Government take
precedence over Finance, and Travel/RideSharing/FoodDelivery
fire before Finance to prevent receipt mis-classification.

AnalyticsService: maps all 14 new slugs to category counts.
client.js: folderToRequest() handles all 14 new slugs.
Layout.jsx: SMART_FOLDERS extended with icons and labels.
widgets.jsx: CAT_SLUG updated for dashboard drillthrough.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/widgets.jsx

@@ -105,20 +105,34 @@ const DOW = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];
 
 // Maps EmailCategory enum name → folder slug or search query
 const CAT_SLUG = {
-  Finance:      '/app/folder/finance',
-  Social:       '/app/folder/social',
-  Notification: '/app/folder/automated',
-  Promotional:  '/app/folder/shopping',
-  Shopping:     '/app/folder/shopping',
-  Gaming:       '/app/folder/gaming',
-  RideSharing:  '/app/folder/ridesharing',
-  FoodDelivery: '/app/folder/food',
-  SeasonalSales:'/app/folder/sales',
-  Wellness:     '/app/folder/wellness',
-  Spam:         '/app/folder/spam',
-  Newsletter:   '/app/search?q=newsletter',
-  Personal:     '/app/search?q=is:unread',
-  Unknown:      '/app/folder/allmail',
+  Finance:          '/app/folder/finance',
+  Social:           '/app/folder/social',
+  Notification:     '/app/folder/automated',
+  Promotional:      '/app/folder/shopping',
+  Shopping:         '/app/folder/shopping',
+  Gaming:           '/app/folder/gaming',
+  RideSharing:      '/app/folder/ridesharing',
+  FoodDelivery:     '/app/folder/food',
+  SeasonalSales:    '/app/folder/sales',
+  Wellness:         '/app/folder/wellness',
+  Travel:           '/app/folder/travel',
+  Subscriptions:    '/app/folder/subscriptions',
+  Parcels:          '/app/folder/parcels',
+  Recruitment:      '/app/folder/recruitment',
+  Events:           '/app/folder/events',
+  SecurityAlerts:   '/app/folder/security',
+  Healthcare:       '/app/folder/healthcare',
+  Education:        '/app/folder/education',
+  NewsMedia:        '/app/folder/news',
+  PropertyUtilities:'/app/folder/property',
+  Charity:          '/app/folder/charity',
+  Government:       '/app/folder/government',
+  CryptoInvesting:  '/app/folder/crypto',
+  FamilySchool:     '/app/folder/family',
+  Spam:             '/app/folder/spam',
+  Newsletter:       '/app/search?q=newsletter',
+  Personal:         '/app/search?q=is:unread',
+  Unknown:          '/app/folder/allmail',
 };
 
 export function CategoryHeatmapWidget() {