feat: Refactor outlets with multilingual support and dynamic queries

- Replace static articles array with dynamic source_keyword queries
- Use MongoDB _id as unique identifier for outlets
- Add multilingual translations (9 languages: ko, en, zh_cn, zh_tw, ja, fr, de, es, it)
- Add OutletService for database operations
- Add outlet migration script with Korean source_keyword matching
- Remove JSON file-based outlet loading
- Add /outlets/{outlet_id}/articles endpoint for dynamic article retrieval

This resolves the design issues with:
1. Static articles array requiring constant updates
2. Lack of multilingual support for outlet names/descriptions
3. Broken image URLs
4. Korean entity matching for article queries

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

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

services/news-api/backend/scripts/migrate_article_source_keywords.py

@@ -0,0 +1,129 @@
+"""
+Script to add source_keyword field to existing articles based on outlet mappings
+"""
+import asyncio
+import os
+from motor.motor_asyncio import AsyncIOMotorClient
+
+# MongoDB connection settings
+MONGODB_URL = os.getenv("MONGODB_URL", "mongodb://localhost:27017")
+DB_NAME = os.getenv("DB_NAME", "news_api_db")
+
+# Supported languages
+LANGUAGES = ["ko", "en", "zh_cn", "zh_tw", "ja", "fr", "de", "es", "it"]
+
+async def migrate_article_source_keywords():
+    """Add source_keyword to articles based on outlet mappings"""
+
+    # Connect to MongoDB
+    client = AsyncIOMotorClient(MONGODB_URL)
+    db = client[DB_NAME]
+    outlets_collection = db.outlets
+
+    # Get all outlets
+    outlets = await outlets_collection.find().to_list(length=None)
+    print(f"Found {len(outlets)} outlets to process")
+
+    # Create mapping from Korean name to source_keyword
+    # Also create reverse mapping for entities matching
+    name_to_keyword = {}
+    for outlet in outlets:
+        # Korean name -> source_keyword
+        name_ko = outlet.get('name') or outlet.get('name_translations', {}).get('ko')
+        if name_ko:
+            name_to_keyword[name_ko] = outlet['source_keyword']
+
+        # Also map the source_keyword to itself for direct matches
+        name_to_keyword[outlet['source_keyword']] = outlet['source_keyword']
+
+    print(f"Created {len(name_to_keyword)} name-to-keyword mappings")
+
+    # Process each language collection
+    total_updated = 0
+    for language in LANGUAGES:
+        collection_name = f"{language}_articles"
+        articles_collection = db[collection_name]
+
+        # Check if collection exists
+        count = await articles_collection.count_documents({})
+        if count == 0:
+            print(f"Skipping empty collection: {collection_name}")
+            continue
+
+        print(f"\nProcessing {collection_name} ({count} articles)...")
+
+        # Process articles in batches
+        batch_size = 100
+        updated_in_lang = 0
+
+        cursor = articles_collection.find({})
+        batch = []
+
+        async for article in cursor:
+            # Extract entities
+            entities = article.get('entities', {})
+            people = entities.get('people', [])
+            organizations = entities.get('organizations', [])
+            groups = entities.get('groups', [])
+
+            # Try to find matching source_keyword
+            source_keyword = None
+
+            # Check people first (most common)
+            for person in people:
+                if person in name_to_keyword:
+                    source_keyword = name_to_keyword[person]
+                    break
+
+            # Then check organizations
+            if not source_keyword:
+                for org in organizations:
+                    if org in name_to_keyword:
+                        source_keyword = name_to_keyword[org]
+                        break
+
+            # Then check groups
+            if not source_keyword:
+                for group in groups:
+                    if group in name_to_keyword:
+                        source_keyword = name_to_keyword[group]
+                        break
+
+            # If found, update the article
+            if source_keyword:
+                batch.append({
+                    '_id': article['_id'],
+                    'source_keyword': source_keyword
+                })
+
+                # Execute batch update
+                if len(batch) >= batch_size:
+                    for item in batch:
+                        await articles_collection.update_one(
+                            {'_id': item['_id']},
+                            {'$set': {'source_keyword': item['source_keyword']}}
+                        )
+                    updated_in_lang += len(batch)
+                    print(f"  Updated {updated_in_lang} articles...", end='\r')
+                    batch = []
+
+        # Update remaining batch
+        if batch:
+            for item in batch:
+                await articles_collection.update_one(
+                    {'_id': item['_id']},
+                    {'$set': {'source_keyword': item['source_keyword']}}
+                )
+            updated_in_lang += len(batch)
+
+        print(f"  Updated {updated_in_lang} articles in {collection_name}")
+        total_updated += updated_in_lang
+
+    print(f"\n✓ Migration completed!")
+    print(f"✓ Total articles updated across all languages: {total_updated}")
+
+    # Close connection
+    client.close()
+
+if __name__ == "__main__":
+    asyncio.run(migrate_article_source_keywords())