feat(backend): add market metadata storage and outcomes extension

app/api/routes/api.py

@@ -7,6 +7,8 @@ from app.schemas.dtos import (
     TokenResponse,
     AccountBalanceDTO,
     LedgerEntryDTO,
+    CreateMarketMetadataRequest,
+    ResolveMarketRequest,
     MarketDTO,
     CreateOrderRequest,
     OrderDTO
@@ -24,6 +26,39 @@ async def login_with_wallet(req: UserAuthRequest, session: AsyncSession = Depend
     return TokenResponse(access_token=token, address=req.address.lower())
 
 # ================= Market Routes =================
+@api_router.post("/markets/metadata", response_model=MarketDTO)
+async def create_market_metadata(
+    req: CreateMarketMetadataRequest,
+    current_user: str = Depends(get_current_user),
+    session: AsyncSession = Depends(get_db_session)
+):
+    """保存预测市场的链下元数据 (标题, 描述, 类别, 2~255个选项)"""
+    market_service = MarketService(session)
+    market = await market_service.save_market_metadata(
+        market_address=req.market_address,
+        question_id=req.question_id,
+        title=req.title,
+        description=req.description,
+        category=req.category,
+        outcomes=req.outcomes,
+        resolution_time=req.resolution_time,
+        creator=current_user
+    )
+    return MarketDTO(
+        market_address=market.market_address,
+        question_id=market.question_id,
+        title=market.title,
+        description=market.description,
+        category=market.category,
+        tier=market.tier,
+        creator=market.creator,
+        status=market.status.value if hasattr(market.status, 'value') else str(market.status),
+        outcomes=market.outcomes,
+        winning_outcome=market.winning_outcome,
+        resolution_time=market.resolution_time,
+        created_at=market.created_at
+    )
+
 @api_router.get("/markets", response_model=List[MarketDTO])
 async def get_markets(
     category: Optional[str] = None,