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/app/models/outlet.py

@@ -0,0 +1,47 @@
+from pydantic import BaseModel, Field
+from typing import List, Optional, Dict
+
+class OutletTranslations(BaseModel):
+    ko: Optional[str] = None
+    en: Optional[str] = None
+    zh_cn: Optional[str] = None
+    zh_tw: Optional[str] = None
+    ja: Optional[str] = None
+    fr: Optional[str] = None
+    de: Optional[str] = None
+    es: Optional[str] = None
+    it: Optional[str] = None
+
+class OutletBase(BaseModel):
+    source_keyword: str  # Used to query articles dynamically
+    category: str  # people, topics, companies
+    name_translations: OutletTranslations = Field(default_factory=lambda: OutletTranslations())
+    description_translations: OutletTranslations = Field(default_factory=lambda: OutletTranslations())
+    image: Optional[str] = None
+
+    # Deprecated - kept for backward compatibility during migration
+    name: Optional[str] = None
+    description: Optional[str] = None
+
+class OutletCreate(OutletBase):
+    pass
+
+class OutletUpdate(BaseModel):
+    source_keyword: Optional[str] = None
+    category: Optional[str] = None
+    name_translations: Optional[OutletTranslations] = None
+    description_translations: Optional[OutletTranslations] = None
+    image: Optional[str] = None
+
+    # Deprecated
+    name: Optional[str] = None
+    description: Optional[str] = None
+    articles: Optional[List[str]] = None
+
+class Outlet(OutletBase):
+    class Config:
+        from_attributes = True
+
+class OutletList(BaseModel):
+    outlets: List[Outlet]
+    total: int