feat: [client] 거래처 API 2차 필드 추가 및 견적 계획 업데이트

- 거래처 유형(client_type), 연락처(mobile, fax), 담당자 정보 필드 추가
- 발주처 설정(account_id/password, payment_day) 필드 추가
- 약정 세금(tax_agreement, tax_amount, tax_start/end_date) 필드 추가
- 악성채권(bad_debt 관련 5개 필드) 정보 필드 추가
- Model, Service, FormRequest, Swagger 문서 업데이트
- 견적 API 계획에 문서 발송 API(email/fax/kakao) 요구사항 추가

database/migrations/2025_12_04_205603_add_extended_fields_to_clients_table.php

@@ -0,0 +1,82 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     * 거래처 2차 확장 필드 추가 (sam-design 기준)
+     */
+    public function up(): void
+    {
+        Schema::table('clients', function (Blueprint $table) {
+            // 기본 정보
+            $table->enum('client_type', ['매입', '매출', '매입매출'])->default('매입')->after('is_active')->comment('거래처 유형');
+
+            // 연락처 정보
+            $table->string('mobile', 20)->nullable()->after('phone')->comment('모바일 번호');
+            $table->string('fax', 20)->nullable()->after('mobile')->comment('팩스 번호');
+
+            // 담당자 정보
+            $table->string('manager_name', 50)->nullable()->after('contact_person')->comment('담당자명');
+            $table->string('manager_tel', 20)->nullable()->after('manager_name')->comment('담당자 전화');
+            $table->string('system_manager', 50)->nullable()->after('manager_tel')->comment('시스템 관리자');
+
+            // 발주처 설정
+            $table->string('account_id', 50)->nullable()->after('address')->comment('계정 ID');
+            $table->string('account_password', 255)->nullable()->after('account_id')->comment('비밀번호 (암호화)');
+            $table->string('purchase_payment_day', 20)->nullable()->after('account_password')->comment('매입 결제일');
+            $table->string('sales_payment_day', 20)->nullable()->after('purchase_payment_day')->comment('매출 결제일');
+
+            // 약정 세금
+            $table->boolean('tax_agreement')->default(false)->after('business_item')->comment('세금 약정 여부');
+            $table->decimal('tax_amount', 15, 2)->nullable()->after('tax_agreement')->comment('약정 금액');
+            $table->date('tax_start_date')->nullable()->after('tax_amount')->comment('약정 시작일');
+            $table->date('tax_end_date')->nullable()->after('tax_start_date')->comment('약정 종료일');
+
+            // 악성채권 정보
+            $table->boolean('bad_debt')->default(false)->after('tax_end_date')->comment('악성채권 여부');
+            $table->decimal('bad_debt_amount', 15, 2)->nullable()->after('bad_debt')->comment('악성채권 금액');
+            $table->date('bad_debt_receive_date')->nullable()->after('bad_debt_amount')->comment('채권 발생일');
+            $table->date('bad_debt_end_date')->nullable()->after('bad_debt_receive_date')->comment('채권 만료일');
+            $table->enum('bad_debt_progress', ['협의중', '소송중', '회수완료', '대손처리'])->nullable()->after('bad_debt_end_date')->comment('진행 상태');
+
+            // 기타 정보
+            $table->text('memo')->nullable()->after('bad_debt_progress')->comment('메모');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('clients', function (Blueprint $table) {
+            $table->dropColumn([
+                'client_type',
+                'mobile',
+                'fax',
+                'manager_name',
+                'manager_tel',
+                'system_manager',
+                'account_id',
+                'account_password',
+                'purchase_payment_day',
+                'sales_payment_day',
+                'tax_agreement',
+                'tax_amount',
+                'tax_start_date',
+                'tax_end_date',
+                'bad_debt',
+                'bad_debt_amount',
+                'bad_debt_receive_date',
+                'bad_debt_end_date',
+                'bad_debt_progress',
+                'memo',
+            ]);
+        });
+    }
+};