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/Http/Controllers/Api/DashboardController.php

@@ -0,0 +1,114 @@
+<?php
+
+namespace App\Http\Controllers\Api;
+
+use App\Models\Expense;
+use Illuminate\Support\Facades\Auth;
+use Carbon\Carbon;
+use App\Http\Controllers\Controller;
+use Illuminate\Support\Facades\DB;
+
+class DashboardController extends Controller
+{
+    public function index()
+    {
+        $userId = Auth::id();
+        $now    = Carbon::now();
+
+        // 1. 本月基礎統計 (用一個查詢同時撈出「總金額」與「總筆數」)
+        $monthStats = Expense::where('user_id', $userId)
+            ->whereYear('date',  $now->year)
+            ->whereMonth('date', $now->month)
+            ->selectRaw('SUM(amount) as total_amount, COUNT(id) as total_count')
+            ->first();
+
+        $monthlyTotal = (float) ($monthStats->total_amount ?? 0);
+        $monthlyCount = (int) ($monthStats->total_count ?? 0);
+
+        // 2. 本月分類統計（圓餅圖）- 保持集合操作即可
+        $categoryStats = Expense::with('category')
+            ->where('user_id', $userId)
+            ->whereYear('date',  $now->year)
+            ->whereMonth('date', $now->month)
+            ->get()
+            ->groupBy(fn($e) => $e->category?->name ?? '未分類')
+            ->map(fn($group, $name) => [
+                'name'   => $name,
+                'total'  => (float) $group->sum('amount'),
+                'color'  => $group->first()->category?->color ?? '#6B7280',
+            ])
+            ->values();
+
+        // 3. 近 6 個月趨勢優化：一次性撈出半年內的所有資料，避免 6 次 SQL 查詢
+        $sixMonthsAgo = $now->copy()->subMonths(5)->startOfMonth();
+        $endOfCurrentMonth = $now->copy()->endOfMonth();
+
+        // 建立近 6 個月的初始月份清單（例如 ['2026/01' => 0.0, '2026/02' => 0.0 ... ]）
+        $monthlyTrendData = collect(range(5, 0))->mapWithKeys(function ($i) use ($now) {
+            $monthStr = $now->copy()->subMonths($i)->format('Y/m');
+            return [$monthStr => 0.0];
+        })->toArray();
+
+        // ➔ (A) 撈取一般消費 (未開啟分攤)
+        $isPostgres = DB::connection()->getDriverName() === 'pgsql';
+        $dateGroupRaw = $isPostgres ? "to_char(date, 'YYYY/MM')" : "DATE_FORMAT(date, '%Y/%m')";
+
+        $normalExpenses = Expense::where('user_id', $userId)
+            ->where('is_amortized', false)
+            ->where('date', '>=', $sixMonthsAgo)
+            ->selectRaw("{$dateGroupRaw} as month, SUM(amount) as total")
+            ->groupBy('month')
+            ->get();
+
+        foreach ($normalExpenses as $expense) {
+            if (array_key_exists($expense->month, $monthlyTrendData)) {
+                $monthlyTrendData[$expense->month] += (float) $expense->total;
+            }
+        }
+
+        // ➔ (B) 智慧分攤消費 (處理跨月、跨年、半年繳大魔王 🎯)
+        // 撈出所有歸屬期間有交集到這 6 個月範圍內的分攤費用
+        $amortizedExpenses = Expense::where('user_id', $userId)
+            ->where('is_amortized', true)
+            ->where(function ($query) use ($sixMonthsAgo, $endOfCurrentMonth) {
+                $query->where('period_start', '<=', $endOfCurrentMonth)
+                    ->where('period_end', '>=', $sixMonthsAgo);
+            })
+            ->get();
+
+        foreach ($amortizedExpenses as $expense) {
+            $start = Carbon::parse($expense->period_start)->startOfMonth();
+            $end = Carbon::parse($expense->period_end)->endOfMonth();
+
+            // 計算這筆費用的總跨月份數 (至少為 1 個月)
+            $totalMonths = max(1, $start->diffInMonths($end) + 1);
+            // 算出每月平均攤提金額
+            $monthlyShare = (float) $expense->amount / $totalMonths;
+
+            // 跑這 6 個月的迴圈，看有沒有落在這筆費用的歸屬區間內
+            foreach ($monthlyTrendData as $monthStr => $currentTotal) {
+                $currentMonthObj = Carbon::createFromFormat('Y/m', $monthStr)->startOfMonth();
+
+                // 如果圖表上的這個月份，剛好在費用的歸屬起訖之內，就把每月平均金額灌進去！
+                if ($currentMonthObj->betweenIncluded($start, $end)) {
+                    $monthlyTrendData[$monthStr] += $monthlyShare;
+                }
+            }
+        }
+
+        // 轉回前端圖表要的格式
+        $monthlyTrend = collect($monthlyTrendData)->map(function ($total, $monthStr) {
+            return [
+                'month' => $monthStr,
+                'total' => round($total, 2), // 四捨五入到小數點兩位
+            ];
+        })->values();
+
+        return response()->json([
+            'monthlyTotal'  => $monthlyTotal,
+            'monthlyCount'  => $monthlyCount,
+            'categoryStats' => $categoryStats,
+            'monthlyTrend'  => $monthlyTrend,
+        ]);
+    }
+}