feat:journal_entries에 source_type, source_key 컬럼 추가

- 원본 거래 추적용 source_type(bank_transaction, hometax_invoice, manual) 컬럼 추가
- 원본 거래 고유키 source_key 컬럼 추가
- tenant_id + source_type + source_key 복합 인덱스 추가

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

database/migrations/2026_02_10_100000_add_source_fields_to_journal_entries.php

@@ -0,0 +1,28 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table('journal_entries', function (Blueprint $table) {
+            $table->string('source_type', 30)->nullable()->after('status')
+                ->comment('원본 거래 유형: bank_transaction, hometax_invoice, manual');
+            $table->string('source_key', 255)->nullable()->after('source_type')
+                ->comment('원본 거래 고유키');
+
+            $table->index(['tenant_id', 'source_type', 'source_key'], 'je_source_idx');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('journal_entries', function (Blueprint $table) {
+            $table->dropIndex('je_source_idx');
+            $table->dropColumn(['source_type', 'source_key']);
+        });
+    }
+};