chore: restructure project into backend and frontend folders

- Move all frontend code to frontend/ directory
- Add backend/ with Go project structure (cmd, internal, pkg)
- Add docker-compose.yml for orchestration

frontend/src/stores/deliveryStore.ts

@@ -0,0 +1,83 @@
+import { create } from 'zustand';
+import { persist } from 'zustand/middleware';
+import type { Delivery } from '../types';
+
+interface DeliveryState {
+  deliveries: Delivery[];
+  addDelivery: (delivery: Omit<Delivery, 'id' | 'createdAt' | 'updatedAt'>) => void;
+  updateDelivery: (id: string, updates: Partial<Delivery>) => void;
+  deleteDelivery: (id: string) => void;
+  toggleStatus: (id: string) => void;
+  getDeliveriesByDate: (date: string) => Delivery[];
+  getDeliveriesByDateRange: (startDate: string, endDate: string) => Delivery[];
+  getDeliveryCountsByDate: () => Record<string, number>;
+}
+
+const STORAGE_KEY = 'delivery-tracker-data';
+
+export const useDeliveryStore = create<DeliveryState>()(
+  persist(
+    (set, get) => ({
+      deliveries: [],
+
+      addDelivery: (delivery) => {
+        const now = Date.now();
+        const newDelivery: Delivery = {
+          ...delivery,
+          id: crypto.randomUUID(),
+          createdAt: now,
+          updatedAt: now,
+        };
+        set((state) => ({
+          deliveries: [...state.deliveries, newDelivery],
+        }));
+      },
+
+      updateDelivery: (id, updates) => {
+        set((state) => ({
+          deliveries: state.deliveries.map((d) =>
+            d.id === id ? { ...d, ...updates, updatedAt: Date.now() } : d
+          ),
+        }));
+      },
+
+      deleteDelivery: (id) => {
+        set((state) => ({
+          deliveries: state.deliveries.filter((d) => d.id !== id),
+        }));
+      },
+
+      toggleStatus: (id) => {
+        set((state) => ({
+          deliveries: state.deliveries.map((d) =>
+            d.id === id
+              ? { ...d, status: d.status === 'new' ? 'delivered' : 'new', updatedAt: Date.now() }
+              : d
+          ),
+        }));
+      },
+
+      getDeliveriesByDate: (date) => {
+        return get().deliveries.filter((d) => d.date === date);
+      },
+
+      getDeliveriesByDateRange: (startDate, endDate) => {
+        return get().deliveries.filter((d) => {
+          const date = d.date;
+          return date >= startDate && date <= endDate;
+        });
+      },
+
+      getDeliveryCountsByDate: () => {
+        const counts: Record<string, number> = {};
+        get().deliveries.forEach((d) => {
+          counts[d.date] = (counts[d.date] || 0) + 1;
+        });
+        return counts;
+      },
+    }),
+    {
+      name: STORAGE_KEY,
+    }
+  )
+);