refactor: restructure project directories for better modularity

- Delete llm/ dead code (3 files, zero references)
- Split mcp/ into sub-packages: mcp/provider/ (8 providers) and
  mcp/payment/ (4 payment clients) with registry pattern
- Export Client internal fields and ClientHooks interface for
  sub-package access
- Split api/server.go (3892 lines) into 8 domain-specific handler files
- Split trader/auto_trader.go (2296 lines) into 5 focused files
- Reorganize web/src/components/ flat files into auth/, charts/,
  trader/, common/, modals/, backtest/ subdirectories
- Update all consumer imports to use registry-based provider creation

web/src/components/common/Container.tsx

@@ -0,0 +1,40 @@
+import { ReactNode, CSSProperties } from 'react'
+
+interface ContainerProps {
+  children: ReactNode
+  className?: string
+  as?: 'div' | 'main' | 'header' | 'section'
+  style?: CSSProperties
+  /** 是否充满宽度（取消 max-width） */
+  fluid?: boolean
+  /** 是否取消水平内边距 */
+  noPadding?: boolean
+  /** 自定义最大宽度类（默认 max-w-[1920px]） */
+  maxWidthClass?: string
+}
+
+/**
+ * 统一的容器组件，确保所有页面元素使用一致的最大宽度和内边距
+ * - max-width: 1920px
+ * - padding: 24px (mobile) -> 32px (tablet) -> 48px (desktop)
+ */
+export function Container({
+  children,
+  className = '',
+  as: Component = 'div',
+  style,
+  fluid = false,
+  noPadding = false,
+  maxWidthClass = 'max-w-[1920px]',
+}: ContainerProps) {
+  const maxWidth = fluid ? 'w-full' : maxWidthClass
+  const padding = noPadding ? 'px-0' : 'px-6 sm:px-8 lg:px-12'
+  return (
+    <Component
+      className={`${maxWidth} mx-auto ${padding} ${className}`}
+      style={style}
+    >
+      {children}
+    </Component>
+  )
+}