Add 'Seed Defaults' button to load all predefined translations

- Add /translations/seed-all-defaults API endpoint
- Loads all DEFAULT_TRANSLATIONS (makers, models, colors, fuels, transmissions)
- Includes 100+ predefined translations (Mohave, Sonata, colors, etc.)
- Add 'Seed Defaults' button to admin translations page

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/api/translations.py

@@ -637,6 +637,47 @@ def fill_default_translations(db: Session = Depends(get_db)):
     return {"message": f"Updated {updated_count} translations with default values"}
 
 
+@router.post("/seed-all-defaults")
+def seed_all_default_translations(db: Session = Depends(get_db)):
+    """
+    Seed ALL translations from the DEFAULT_TRANSLATIONS dictionary into the database.
+    This pre-populates translations for all known terms, not just those in the cars table.
+    """
+    added_count = 0
+    skipped_count = 0
+
+    for category, terms in DEFAULT_TRANSLATIONS.items():
+        for korean_text, translations in terms.items():
+            # Check if already exists
+            existing = db.query(Translation).filter(
+                Translation.source_text == korean_text,
+                Translation.category == category
+            ).first()
+
+            if existing:
+                skipped_count += 1
+                continue
+
+            trans = Translation(
+                source_text=korean_text,
+                category=category,
+                text_en=translations.get("en", korean_text),
+                text_mn=translations.get("mn", korean_text),
+                text_ru=translations.get("ru", korean_text)
+            )
+            db.add(trans)
+            added_count += 1
+
+    db.commit()
+
+    return {
+        "message": f"Seeded {added_count} translations from default dictionary (skipped {skipped_count} existing)",
+        "added": added_count,
+        "skipped": skipped_count,
+        "categories": list(DEFAULT_TRANSLATIONS.keys())
+    }
+
+
 # AI Auto-Translation Service
 import httpx
 import json