feat: 完成進貨單自動拋轉應付帳款流程與AP介面優化

1. 新增 AccountPayable (應付帳款) 模組，包含 Migration、Model、Service 與 Controller
2. 修改 GoodsReceipt (進貨單) 流程，在確認進貨時自動產生對應的應付帳款單 (AP-YYYYMMDD-XX)
3. 實作應付帳款詳細頁面 (Show.tsx)，包含發票登記與標記付款功能
4. 修正應付帳款 Show 頁面的排版，將發票資訊套用標準的綠色背景區塊，並調整按鈕位置
5. 更新相關的 Service Provider 與 Routes

app/Modules/Finance/Models/AccountPayable.php

@@ -0,0 +1,61 @@
+<?php
+
+namespace App\Modules\Finance\Models;
+
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+class AccountPayable extends Model
+{
+    use HasFactory;
+
+    public const STATUS_PENDING = 'pending';
+    public const STATUS_PARTIALLY_PAID = 'partially_paid';
+    public const STATUS_PAID = 'paid';
+    public const STATUS_CANCELLED = 'cancelled';
+
+    protected $fillable = [
+        'vendor_id',
+        'source_document_type',
+        'source_document_id',
+        'document_number',
+        'total_amount',
+        'tax_amount',
+        'status',
+        'due_date',
+        'invoice_number',
+        'invoice_date',
+        'paid_at',
+        'payment_method',
+        'payment_note',
+        'remarks',
+        'created_by',
+    ];
+
+    protected $casts = [
+        'total_amount' => 'decimal:2',
+        'tax_amount' => 'decimal:2',
+        'due_date' => 'date',
+        'invoice_date' => 'date',
+        'paid_at' => 'datetime',
+    ];
+
+    /**
+     * 關聯：供應商
+     * @return BelongsTo
+     */
+    public function vendor(): BelongsTo
+    {
+        return $this->belongsTo(\App\Modules\Procurement\Models\Vendor::class, 'vendor_id');
+    }
+
+    /**
+     * 關聯：建立者
+     * @return BelongsTo
+     */
+    public function creator(): BelongsTo
+    {
+        return $this->belongsTo(\App\Modules\Core\Models\User::class, 'created_by');
+    }
+}