refactor: split app into modular src architecture

src/constants.js

@@ -0,0 +1,20 @@
+export const STORAGE_KEY = 'luggage-list:v2';
+export const TAB_BAR_HEIGHT = 72;
+
+export const ITEM_STATUSES = ['packed', 'unpacked', 'lost', 'left-behind', 'lent-to'];
+export const ITEM_PLACEMENTS = ['suitcase', 'backpack', 'with-user', 'other'];
+
+export const STATUS_COLORS = {
+  packed: '#22c55e',
+  unpacked: '#64748b',
+  lost: '#ef4444',
+  'left-behind': '#f59e0b',
+  'lent-to': '#8b5cf6',
+};
+
+export const emptyData = {
+  trips: [],
+  itemsByTrip: {},
+  checkupsByTrip: {},
+  defaultTemplateTripId: null,
+};