feat: 견적 단가 자동 적용 기능 추가

- 고객 그룹별 단가 조정 지원
- 견적 생성 시 자동 단가 조회
- 매출단가만 사용 (매입단가는 경고)

database/migrations/2025_10_13_213549_create_client_groups_table.php

@@ -0,0 +1,46 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::create('client_groups', function (Blueprint $table) {
+            $table->id();
+            $table->unsignedBigInteger('tenant_id')->comment('테넌트 ID');
+            $table->string('group_code', 30)->comment('그룹 코드');
+            $table->string('group_name', 100)->comment('그룹명');
+            $table->decimal('price_rate', 5, 4)->default(1.0000)->comment('가격 배율 (1.0 = 기준가, 0.9 = 90%, 1.1 = 110%)');
+            $table->tinyInteger('is_active')->default(1)->comment('활성 여부 (1=활성, 0=비활성)');
+
+            // 감사 컬럼
+            $table->unsignedBigInteger('created_by')->nullable()->comment('생성자 ID');
+            $table->unsignedBigInteger('updated_by')->nullable()->comment('수정자 ID');
+            $table->unsignedBigInteger('deleted_by')->nullable()->comment('삭제자 ID');
+
+            $table->timestamps();
+            $table->softDeletes();
+
+            // 인덱스
+            $table->index(['tenant_id', 'is_active']);
+            $table->unique(['tenant_id', 'group_code'], 'uq_client_groups_tenant_code');
+
+            // 외래키
+            $table->foreign('tenant_id')->references('id')->on('tenants')->onDelete('cascade');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::dropIfExists('client_groups');
+    }
+};

database/migrations/2025_10_13_213556_add_client_group_id_to_clients_table.php

@@ -0,0 +1,36 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::table('clients', function (Blueprint $table) {
+            $table->unsignedBigInteger('client_group_id')
+                ->nullable()
+                ->after('tenant_id')
+                ->comment('고객 그룹 ID (NULL = 기본 그룹)');
+
+            $table->index(['tenant_id', 'client_group_id']);
+            $table->foreign('client_group_id')->references('id')->on('client_groups')->onDelete('set null');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('clients', function (Blueprint $table) {
+            $table->dropForeign(['client_group_id']);
+            $table->dropIndex(['tenant_id', 'client_group_id']);
+            $table->dropColumn('client_group_id');
+        });
+    }
+};

database/migrations/2025_10_13_213602_add_client_group_id_to_price_histories_table.php

@@ -0,0 +1,40 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::table('price_histories', function (Blueprint $table) {
+            $table->unsignedBigInteger('client_group_id')
+                ->nullable()
+                ->after('price_type_code')
+                ->comment('고객 그룹 ID (NULL = 기본 가격, 값 있으면 그룹별 차등 가격)');
+
+            // 기존 인덱스에 client_group_id 추가
+            $table->dropIndex('idx_price_histories_main');
+            $table->index(['tenant_id', 'item_type_code', 'item_id', 'client_group_id', 'started_at'], 'idx_price_histories_main');
+
+            $table->foreign('client_group_id')->references('id')->on('client_groups')->onDelete('cascade');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('price_histories', function (Blueprint $table) {
+            $table->dropForeign(['client_group_id']);
+            $table->dropIndex('idx_price_histories_main');
+            $table->index(['tenant_id', 'item_type_code', 'item_id', 'started_at'], 'idx_price_histories_main');
+            $table->dropColumn('client_group_id');
+        });
+    }
+};