feat: Transform to Tauri desktop app

- Initialize Tauri v2 project with Rust backend
- Restructure project: move source files to src/ directory
- Add Tauri configuration for Windows, macOS, and Linux builds
- Update Vite config for Tauri development workflow
- Add file system and dialog permissions for native features
- Update package.json with desktop build scripts
- Update tsconfig.json paths for new src structure
- Add Tauri and desktop badges to README
- Document desktop build process and architecture

src/components/FileUpload.tsx

@@ -0,0 +1,92 @@
+import React, { useCallback, useState } from 'react';
+import { Upload, FileText, AlertCircle } from 'lucide-react';
+
+interface FileUploadProps {
+  onFileLoaded: (content: string) => void;
+}
+
+export const FileUpload: React.FC<FileUploadProps> = ({ onFileLoaded }) => {
+  const [dragActive, setDragActive] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+
+  const handleFile = (file: File) => {
+    setError(null);
+    if (!file.name.endsWith('.md') && !file.name.endsWith('.txt') && !file.name.endsWith('.markdown')) {
+      setError('Please upload a Markdown (.md) or Text (.txt) file.');
+      return;
+    }
+
+    const reader = new FileReader();
+    reader.onload = (e) => {
+      const text = e.target?.result;
+      if (typeof text === 'string') {
+        onFileLoaded(text);
+      }
+    };
+    reader.onerror = () => setError('Error reading file.');
+    reader.readAsText(file);
+  };
+
+  const handleDrag = useCallback((e: React.DragEvent) => {
+    e.preventDefault();
+    e.stopPropagation();
+    if (e.type === 'dragenter' || e.type === 'dragover') {
+      setDragActive(true);
+    } else if (e.type === 'dragleave') {
+      setDragActive(false);
+    }
+  }, []);
+
+  const handleDrop = useCallback((e: React.DragEvent) => {
+    e.preventDefault();
+    e.stopPropagation();
+    setDragActive(false);
+    if (e.dataTransfer.files && e.dataTransfer.files[0]) {
+      handleFile(e.dataTransfer.files[0]);
+    }
+  }, []);
+
+  const handleChange = (e: React.ChangeEvent<HTMLInputElement>) => {
+    e.preventDefault();
+    if (e.target.files && e.target.files[0]) {
+      handleFile(e.target.files[0]);
+    }
+  };
+
+  return (
+    <div className="w-full max-w-xl mx-auto">
+      <div
+        className={`relative group flex flex-col items-center justify-center w-full h-64 border-2 border-dashed rounded-2xl transition-all duration-300 ease-in-out cursor-pointer overflow-hidden
+          ${dragActive ? 'border-indigo-500 bg-indigo-500/10' : 'border-zinc-700 bg-zinc-900/50 hover:border-zinc-500 hover:bg-zinc-800/50'}`}
+        onDragEnter={handleDrag}
+        onDragLeave={handleDrag}
+        onDragOver={handleDrag}
+        onDrop={handleDrop}
+      >
+        <input
+          type="file"
+          className="absolute inset-0 w-full h-full opacity-0 cursor-pointer z-10"
+          onChange={handleChange}
+          accept=".md,.txt,.markdown"
+        />
+        
+        <div className="flex flex-col items-center justify-center pt-5 pb-6 text-zinc-400 group-hover:text-zinc-200 transition-colors">
+          <div className={`p-4 rounded-full mb-4 ${dragActive ? 'bg-indigo-500/20 text-indigo-400' : 'bg-zinc-800 text-zinc-500'}`}>
+            <Upload size={32} />
+          </div>
+          <p className="mb-2 text-lg font-medium">
+            <span className="font-semibold text-indigo-400">Click to upload</span> or drag and drop
+          </p>
+          <p className="text-sm text-zinc-500">Markdown or Plain Text files</p>
+        </div>
+      </div>
+
+      {error && (
+        <div className="mt-4 p-4 bg-red-900/20 border border-red-800 rounded-lg flex items-center gap-3 text-red-200 animate-in fade-in slide-in-from-top-2">
+          <AlertCircle size={20} />
+          <span>{error}</span>
+        </div>
+      )}
+    </div>
+  );
+};