refactor: 移除工具栏 Gitee 按钮，项目地址移至关于弹框

- 工具栏移除 Gitee 图标按钮
- 关于弹框添加项目地址链接（带 Gitee 图标）
- 链接点击跳转到 gitee.com/thzxx/MarkLite

src/renderer/App.tsx

@@ -19,7 +19,7 @@ import { WelcomeScreen } from './components/WelcomeScreen/WelcomeScreen'
 import { Toast } from './components/Toast/Toast'
 import { ModifiedBanner } from './components/ModifiedBanner/ModifiedBanner'
 import { DropOverlay } from './components/DropOverlay/DropOverlay'
-import { AppIcon } from './components/Icons'
+import { AppIcon, Gitee } from './components/Icons'
 
 const APP_VERSION = 'v0.1.0'
 
@@ -268,6 +268,17 @@ export default function App() {
               </div>
             </div>
             <div className="about-footer">
+              <a className="about-link" href="#" onClick={(e) => {
+                e.preventDefault()
+                if (window.electronAPI?.openExternal) {
+                  window.electronAPI.openExternal('https://gitee.com/thzxx/MarkLite')
+                } else {
+                  window.open('https://gitee.com/thzxx/MarkLite', '_blank')
+                }
+              }}>
+                <Gitee size={16} />
+                <span>gitee.com/thzxx/MarkLite</span>
+              </a>
               <p>基于 Electron + React + TypeScript 构建</p>
               <p className="about-copyright">© 2026 thzxx</p>
             </div>

src/renderer/components/Toolbar/Toolbar.tsx

@@ -1,5 +1,5 @@
 import React from 'react'
-import { FolderOpen, Save, EditMode, PreviewMode, Moon, Sun, Gitee, Info } from '../Icons'
+import { FolderOpen, Save, EditMode, PreviewMode, Moon, Sun, Info } from '../Icons'
 
 interface ToolbarProps {
   onOpen: () => void
@@ -12,14 +12,6 @@ interface ToolbarProps {
 }
 
 export function Toolbar({ onOpen, onSave, viewMode, onViewModeChange, darkMode, onToggleDark, onShowAbout }: ToolbarProps) {
-  const handleOpenGitee = () => {
-    if (window.electronAPI?.openExternal) {
-      window.electronAPI.openExternal('https://gitee.com/thzxx/MarkLite')
-    } else {
-      window.open('https://gitee.com/thzxx/MarkLite', '_blank')
-    }
-  }
-
   return (
     <div id="toolbar">
       <div className="toolbar-left">
@@ -45,9 +37,6 @@ export function Toolbar({ onOpen, onSave, viewMode, onViewModeChange, darkMode,
         <button className="toolbar-btn" onClick={onToggleDark} title="切换暗色主题">
           {darkMode ? <Sun size={18} /> : <Moon size={18} />}
         </button>
-        <button className="toolbar-btn" onClick={handleOpenGitee} title="Gitee 项目主页">
-          <Gitee size={18} />
-        </button>
         <button className="toolbar-btn" onClick={onShowAbout} title="关于">
           <Info size={18} />
         </button>

src/renderer/styles/global.css

@@ -1161,6 +1161,26 @@ html, body {
   margin-bottom: 20px;
 }
 
+.about-link {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  color: var(--primary);
+  text-decoration: none;
+  font-size: 13px;
+  margin-bottom: 8px;
+  padding: 6px 12px;
+  border-radius: 6px;
+  background: var(--primary-light);
+  transition: all 0.15s ease;
+  cursor: pointer;
+}
+
+.about-link:hover {
+  background: var(--primary);
+  color: white;
+}
+
 .about-footer p {
   color: var(--text-tertiary);
   font-size: 12px;