refactor(web): replace all hardcoded SVG icons with lucide-react

Unify icon usage across the entire frontend by replacing 67 hardcoded
SVG icons with lucide-react components across ~25 files. This improves
consistency, maintainability, and reduces bundle duplication.

Key replacements:
- Sidebar nav: Zap, LayoutDashboard, Bot, Workflow, BookMarked, etc.
- MCP forms: Loader2, XCircle, Trash2
- Monitoring: Sparkles, MessageSquare, CheckCircle2, RefreshCw, etc.
- Cards: Clock, Star, Workflow, Hexagon, Puzzle, Github, etc.
- Misc: Paperclip, AudioLines, CloudUpload, Layers, Heart, Smile

Zero hardcoded <svg> tags remain in .tsx files.

web/src/app/home/pipelines/components/debug-dialog/ImagePreviewDialog.tsx

@@ -1,4 +1,5 @@
 import React from 'react';
+import { X } from 'lucide-react';
 
 interface ImagePreviewDialogProps {
   open: boolean;
@@ -28,19 +29,7 @@ export default function ImagePreviewDialog({
           onClick={onClose}
           className="self-end w-9 h-9 rounded-full bg-white hover:bg-gray-100 dark:bg-gray-800 dark:hover:bg-gray-700 text-gray-800 dark:text-gray-100 shadow-lg transition-all hover:scale-105 flex items-center justify-center"
         >
-          <svg
-            className="w-4 h-4"
-            fill="none"
-            viewBox="0 0 24 24"
-            stroke="currentColor"
-          >
-            <path
-              strokeLinecap="round"
-              strokeLinejoin="round"
-              strokeWidth={2}
-              d="M6 18L18 6M6 6l12 12"
-            />
-          </svg>
+          <X className="w-4 h-4" />
         </button>
 
         {/* 图片 */}