feat: add admin orders management

- Add admin API endpoints for order management
- Add orders page with vendor selector and filtering
- Add order schemas for admin operations
- Support order status tracking and management

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

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

models/schema/order.py

@@ -162,3 +162,96 @@ class OrderListResponse(BaseModel):
     total: int
     skip: int
     limit: int
+
+
+# ============================================================================
+# Admin Order Schemas
+# ============================================================================
+
+
+class AdminOrderItem(BaseModel):
+    """Order item with vendor info for admin list view."""
+
+    model_config = ConfigDict(from_attributes=True)
+
+    id: int
+    vendor_id: int
+    vendor_name: str | None = None
+    vendor_code: str | None = None
+    customer_id: int
+    customer_name: str | None = None
+    customer_email: str | None = None
+    order_number: str
+    channel: str
+    status: str
+
+    # Financial
+    subtotal: float
+    tax_amount: float
+    shipping_amount: float
+    discount_amount: float
+    total_amount: float
+    currency: str
+
+    # Shipping
+    shipping_method: str | None
+    tracking_number: str | None
+
+    # Item count
+    item_count: int = 0
+
+    # Timestamps
+    created_at: datetime
+    updated_at: datetime
+    paid_at: datetime | None
+    shipped_at: datetime | None
+    delivered_at: datetime | None
+    cancelled_at: datetime | None
+
+
+class AdminOrderListResponse(BaseModel):
+    """Cross-vendor order list for admin."""
+
+    orders: list[AdminOrderItem]
+    total: int
+    skip: int
+    limit: int
+
+
+class AdminOrderStats(BaseModel):
+    """Order statistics for admin dashboard."""
+
+    total_orders: int
+    pending_orders: int
+    processing_orders: int
+    shipped_orders: int
+    delivered_orders: int
+    cancelled_orders: int
+    refunded_orders: int
+    total_revenue: float
+    vendors_with_orders: int
+
+
+class AdminOrderStatusUpdate(BaseModel):
+    """Admin version of status update with reason."""
+
+    status: str = Field(
+        ..., pattern="^(pending|processing|shipped|delivered|cancelled|refunded)$"
+    )
+    tracking_number: str | None = None
+    reason: str | None = Field(None, description="Reason for status change")
+
+
+class AdminVendorWithOrders(BaseModel):
+    """Vendor with order count."""
+
+    id: int
+    name: str
+    vendor_code: str
+    order_count: int = 0
+
+
+class AdminVendorsWithOrdersResponse(BaseModel):
+    """Response for vendors with orders list."""
+
+    vendors: list[AdminVendorWithOrders]