Add membership fee system with disability discount and fix document permissions

Features:
- Implement two fee types: entrance fee and annual fee (both NT$1,000)
- Add 50% discount for disability certificate holders
- Add disability certificate upload in member profile
- Integrate disability verification into cashier approval workflow
- Add membership fee settings in system admin

Document permissions:
- Fix hard-coded role logic in Document model
- Use permission-based authorization instead of role checks

Additional features:
- Add announcements, general ledger, and trial balance modules
- Add income management and accounting entries
- Add comprehensive test suite with factories
- Update UI translations to Traditional Chinese

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/Services/MembershipFeeCalculator.php

@@ -0,0 +1,154 @@
+<?php
+
+namespace App\Services;
+
+use App\Models\Member;
+use App\Models\MembershipPayment;
+
+class MembershipFeeCalculator
+{
+    protected SettingsService $settings;
+
+    public function __construct(SettingsService $settings)
+    {
+        $this->settings = $settings;
+    }
+
+    /**
+     * 計算會費金額
+     *
+     * @param Member $member 會員
+     * @param string $feeType 會費類型 (entrance_fee | annual_fee)
+     * @return array{base_amount: float, discount_amount: float, final_amount: float, disability_discount: bool, fee_type: string}
+     */
+    public function calculate(Member $member, string $feeType): array
+    {
+        $baseAmount = $this->getBaseAmount($feeType);
+        $discountRate = $member->hasApprovedDisability()
+            ? $this->getDisabilityDiscountRate()
+            : 0;
+
+        $discountAmount = round($baseAmount * $discountRate, 2);
+        $finalAmount = round($baseAmount - $discountAmount, 2);
+
+        return [
+            'fee_type' => $feeType,
+            'base_amount' => $baseAmount,
+            'discount_amount' => $discountAmount,
+            'final_amount' => $finalAmount,
+            'disability_discount' => $discountRate > 0,
+        ];
+    }
+
+    /**
+     * 為會員計算下一次應繳的會費
+     *
+     * @param Member $member
+     * @return array{base_amount: float, discount_amount: float, final_amount: float, disability_discount: bool, fee_type: string}
+     */
+    public function calculateNextFee(Member $member): array
+    {
+        $feeType = $member->getNextFeeType();
+        return $this->calculate($member, $feeType);
+    }
+
+    /**
+     * 取得基本會費金額
+     *
+     * @param string $feeType
+     * @return float
+     */
+    public function getBaseAmount(string $feeType): float
+    {
+        return match($feeType) {
+            MembershipPayment::FEE_TYPE_ENTRANCE => $this->getEntranceFee(),
+            MembershipPayment::FEE_TYPE_ANNUAL => $this->getAnnualFee(),
+            default => 0,
+        };
+    }
+
+    /**
+     * 取得入會會費金額
+     *
+     * @return float
+     */
+    public function getEntranceFee(): float
+    {
+        return (float) $this->settings->get('membership_fee.entrance_fee', 1000);
+    }
+
+    /**
+     * 取得常年會費金額
+     *
+     * @return float
+     */
+    public function getAnnualFee(): float
+    {
+        return (float) $this->settings->get('membership_fee.annual_fee', 1000);
+    }
+
+    /**
+     * 取得身心障礙折扣比例
+     *
+     * @return float 折扣比例 (0-1)
+     */
+    public function getDisabilityDiscountRate(): float
+    {
+        return (float) $this->settings->get('membership_fee.disability_discount_rate', 0.5);
+    }
+
+    /**
+     * 取得身心障礙折扣百分比 (用於顯示)
+     *
+     * @return int 百分比 (0-100)
+     */
+    public function getDisabilityDiscountPercentage(): int
+    {
+        return (int) ($this->getDisabilityDiscountRate() * 100);
+    }
+
+    /**
+     * 驗證繳費金額是否正確
+     *
+     * @param MembershipPayment $payment
+     * @return bool
+     */
+    public function validatePaymentAmount(MembershipPayment $payment): bool
+    {
+        $member = $payment->member;
+        $expected = $this->calculate($member, $payment->fee_type);
+
+        // 繳費金額應等於或大於應繳金額
+        return $payment->amount >= $expected['final_amount'];
+    }
+
+    /**
+     * 取得會費類型的標籤
+     *
+     * @param string $feeType
+     * @return string
+     */
+    public function getFeeTypeLabel(string $feeType): string
+    {
+        return match($feeType) {
+            MembershipPayment::FEE_TYPE_ENTRANCE => '入會會費',
+            MembershipPayment::FEE_TYPE_ANNUAL => '常年會費',
+            default => $feeType,
+        };
+    }
+
+    /**
+     * 取得所有會費設定（用於管理界面）
+     *
+     * @return array
+     */
+    public function getFeeSettings(): array
+    {
+        return [
+            'entrance_fee' => $this->getEntranceFee(),
+            'annual_fee' => $this->getAnnualFee(),
+            'disability_discount_rate' => $this->getDisabilityDiscountRate(),
+            'disability_discount_percentage' => $this->getDisabilityDiscountPercentage(),
+        ];
+    }
+}