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/trader/Tooltip.tsx

@@ -0,0 +1,44 @@
+import { useState } from 'react'
+
+interface TooltipProps {
+  content: string
+  children: React.ReactNode
+}
+
+export function Tooltip({ content, children }: TooltipProps) {
+  const [show, setShow] = useState(false)
+
+  return (
+    <div className="relative inline-block">
+      <div
+        onMouseEnter={() => setShow(true)}
+        onMouseLeave={() => setShow(false)}
+        onClick={() => setShow(!show)}
+      >
+        {children}
+      </div>
+      {show && (
+        <div
+          className="absolute z-10 px-3 py-2 text-sm rounded-lg shadow-lg w-64 left-1/2 transform -translate-x-1/2 bottom-full mb-2"
+          style={{
+            background: '#2B3139',
+            color: '#EAECEF',
+            border: '1px solid #474D57',
+          }}
+        >
+          {content}
+          <div
+            className="absolute left-1/2 transform -translate-x-1/2 top-full"
+            style={{
+              width: 0,
+              height: 0,
+              borderLeft: '6px solid transparent',
+              borderRight: '6px solid transparent',
+              borderTop: '6px solid #2B3139',
+            }}
+          />
+        </div>
+      )}
+    </div>
+  )
+}