feat: 前端分離+功能api化

1. 新增資產管理CRUD、googleOAuth登入
2. 更改原記帳controller

app/Models/Account.php

@@ -0,0 +1,54 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+
+class Account extends Model
+{
+    protected $fillable = [
+        'user_id',
+        'name',
+        'type',
+        'currency',
+        'balance',
+        'note',
+        'billing_day',
+        'payment_day',
+    ];
+
+    public function user()
+    {
+        return $this->belongsTo(User::class);
+    }
+
+    public function holdings()
+    {
+        return $this->hasMany(InvestmentHolding::class);
+    }
+
+    public function expenses()
+    {
+        return $this->hasMany(Expense::class);
+    }
+
+    public function unpaidAmount()
+    {
+        $billingDay = $this->billing_day ?? 1;
+
+        $now = now();
+
+        // 如果今天還沒到結帳日，帳單週期是上個月結帳日到這個月結帳日
+        if ($now->day < $billingDay) {
+            $start = $now->copy()->subMonth()->setDay($billingDay);
+            $end = $now->copy()->setDay($billingDay)->subDay();
+        } else {
+            $start = $now->copy()->setDay($billingDay);
+            $end = $now->copy()->addMonth()->setDay($billingDay)->subDay();
+        }
+
+        return $this->expenses()
+            ->whereBetween('date', [$start->toDateString(), $end->toDateString()])
+            ->sum('amount');
+    }
+}