refactor: 删除自定义搜索，统一使用 CodeMirror 6 搜索

删除文件：
- SearchBar/SearchBar.tsx — 自定义搜索栏组件
- stores/searchStore.ts — 自定义搜索状态管理
- lib/searchEngine.ts — 自定义搜索匹配引擎
- types/search.ts — 搜索相关类型定义

清理代码：
- App.tsx：移除 SearchBar 导入和渲染
- useKeyboard.ts：移除 searchStore 引用和搜索快捷键
- Editor.tsx：移除 searchStore 引用和搜索逻辑
- types/index.ts：移除 search 类型导出
- global.css：删除旧搜索栏样式（~113 行）

CodeMirror 6 搜索面板移到顶部：
- .cm-panels { top: 0; bottom: auto; }
- .cm-panels-bottom { top: 0; bottom: auto; }

快捷键（CodeMirror 内置）：
- Ctrl+F 搜索
- Ctrl+H 替换
- Enter/Shift+Enter 下一个/上一个
- Alt+C 大小写
- Alt+R 正则

src/renderer/components/Editor/Editor.tsx

@@ -1,6 +1,5 @@
 import React, { useEffect, useCallback } from 'react'
 import { useTabStore } from '../../stores/tabStore'
-import { useSearchStore } from '../../stores/searchStore'
 import { useCodeMirror } from './useCodeMirror'
 import { EditorToolbar } from './EditorToolbar'
 
@@ -20,12 +19,10 @@ export function Editor({ darkMode }: EditorProps) {
     containerRef,
     viewRef,
     setContent,
-    getContent,
     getScrollTop,
     setScrollTop,
     getSelection,
-    setSelection,
-    scrollTo
+    setSelection
   } = useCodeMirror({
     content: activeTab?.content ?? '',
     onChange: useCallback((value: string) => {
@@ -43,15 +40,13 @@ export function Editor({ darkMode }: EditorProps) {
   useEffect(() => {
     if (!activeTab) return
     setContent(activeTab.content)
-
-    // 恢复滚动和选区
     requestAnimationFrame(() => {
       setScrollTop(activeTab.scrollTop)
       setSelection(activeTab.selectionStart, activeTab.selectionEnd)
     })
   }, [activeTabId])
 
-  // 保存当前标签状态（切换前）
+  // 保存当前标签状态
   useEffect(() => {
     return () => {
       if (!activeTabId) return
@@ -63,12 +58,10 @@ export function Editor({ darkMode }: EditorProps) {
     }
   }, [activeTabId])
 
-  // 搜索：Ctrl+F 聚焦搜索框，Enter 导航
+  // Ctrl+B 粗体, Ctrl+I 斜体
   useEffect(() => {
     const handleKeyDown = (e: KeyboardEvent) => {
       const isCtrl = e.ctrlKey || e.metaKey
-
-      // Ctrl+B 粗体
       if (isCtrl && e.key === 'b') {
         e.preventDefault()
         const view = viewRef.current
@@ -80,8 +73,6 @@ export function Editor({ darkMode }: EditorProps) {
           selection: { anchor: from + 2, head: from + 2 + selected.length }
         })
       }
-
-      // Ctrl+I 斜体
       if (isCtrl && e.key === 'i') {
         e.preventDefault()
         const view = viewRef.current
@@ -94,7 +85,6 @@ export function Editor({ darkMode }: EditorProps) {
         })
       }
     }
-
     document.addEventListener('keydown', handleKeyDown)
     return () => document.removeEventListener('keydown', handleKeyDown)
   }, [viewRef])

src/renderer/components/SearchBar/SearchBar.tsx

@@ -1,147 +0,0 @@
-import React, { useCallback, useRef, useEffect } from 'react'
-import { useSearchStore } from '../../stores/searchStore'
-import { useTabStore } from '../../stores/tabStore'
-import { findMatches } from '../../lib/searchEngine'
-import { ChevronUp, ChevronDown, X } from '../Icons'
-
-export function SearchBar() {
-  const searchInputRef = useRef<HTMLInputElement>(null)
-
-  const isVisible = useSearchStore(s => s.isVisible)
-  const showReplace = useSearchStore(s => s.showReplace)
-  const searchText = useSearchStore(s => s.searchText)
-  const replaceText = useSearchStore(s => s.replaceText)
-  const matches = useSearchStore(s => s.matches)
-  const currentIndex = useSearchStore(s => s.currentIndex)
-  const options = useSearchStore(s => s.options)
-  const setSearchText = useSearchStore(s => s.setSearchText)
-  const setReplaceText = useSearchStore(s => s.setReplaceText)
-  const setShowReplace = useSearchStore(s => s.setShowReplace)
-  const setMatches = useSearchStore(s => s.setMatches)
-  const findNext = useSearchStore(s => s.findNext)
-  const findPrev = useSearchStore(s => s.findPrev)
-  const toggleCaseSensitive = useSearchStore(s => s.toggleCaseSensitive)
-  const toggleRegex = useSearchStore(s => s.toggleRegex)
-  const close = useSearchStore(s => s.close)
-
-  const getActiveTab = useTabStore(s => s.getActiveTab)
-
-  const doSearch = useCallback((text: string) => {
-    const tab = getActiveTab()
-    if (!tab || !text) {
-      setMatches([])
-      return
-    }
-    const found = findMatches(tab.content, text, options)
-    setMatches(found)
-  }, [getActiveTab, options, setMatches])
-
-  const handleSearchChange = useCallback((e: React.ChangeEvent<HTMLInputElement>) => {
-    const text = e.target.value
-    setSearchText(text)
-    // Editor 会监听 searchText 变化并执行搜索和高亮
-  }, [setSearchText])
-
-  const handleReplaceCurrent = useCallback(() => {
-    const tab = getActiveTab()
-    if (!tab || matches.length === 0 || currentIndex < 0) return
-    const m = matches[currentIndex]
-    const newContent = tab.content.substring(0, m.start) + replaceText + tab.content.substring(m.end)
-    useTabStore.getState().updateTabContent(tab.id, newContent)
-    doSearch(searchText)
-  }, [getActiveTab, matches, currentIndex, replaceText, searchText, doSearch])
-
-  // B-02: 全部替换（从后向前逐个替换）
-  const handleReplaceAll = useCallback(() => {
-    const tab = getActiveTab()
-    if (!tab || matches.length === 0) return
-    let result = tab.content
-    for (let i = matches.length - 1; i >= 0; i--) {
-      const m = matches[i]
-      result = result.substring(0, m.start) + replaceText + result.substring(m.end)
-    }
-    useTabStore.getState().updateTabContent(tab.id, result)
-    doSearch(searchText)
-  }, [getActiveTab, matches, replaceText, searchText, doSearch])
-
-  useEffect(() => {
-    if (isVisible && searchInputRef.current) {
-      searchInputRef.current.focus()
-    }
-  }, [isVisible])
-
-  if (!isVisible) return null
-
-  return (
-    <div id="search-bar">
-      <div className="search-row">
-        <button
-          id="btn-toggle-replace"
-          className={`search-opt-btn ${showReplace ? 'expanded' : ''}`}
-          onClick={() => setShowReplace(!showReplace)}
-          title="展开替换行"
-        >
-          ▾
-        </button>
-        <input
-          ref={searchInputRef}
-          type="text"
-          id="search-input"
-          placeholder="查找..."
-          value={searchText}
-          onChange={handleSearchChange}
-          onKeyDown={(e) => {
-            if (e.key === 'Enter') {
-              e.preventDefault()
-              e.shiftKey ? findPrev() : findNext()
-            }
-            if (e.key === 'Escape') {
-              e.preventDefault()
-              close()
-            }
-          }}
-        />
-        <span id="search-count">
-          {matches.length > 0 ? `${currentIndex + 1}/${matches.length}` : searchText ? '无结果' : ''}
-        </span>
-        <button
-          className={`search-opt-btn ${options.caseSensitive ? 'active' : ''}`}
-          onClick={toggleCaseSensitive}
-          title="区分大小写 (Alt+C)"
-        >
-          Aa
-        </button>
-        <button
-          className={`search-opt-btn ${options.useRegex ? 'active' : ''}`}
-          onClick={toggleRegex}
-          title="正则表达式 (Alt+R)"
-        >
-          .*
-        </button>
-        <button className="search-nav-btn" onClick={findPrev} title="上一个 (Shift+Enter)">
-          <ChevronUp size={12} />
-        </button>
-        <button className="search-nav-btn" onClick={findNext} title="下一个 (Enter)">
-          <ChevronDown size={12} />
-        </button>
-        <button className="search-nav-btn" onClick={close} title="关闭 (Escape)">
-          <X size={14} />
-        </button>
-      </div>
-
-      {showReplace && (
-        <div id="replace-row">
-          <input
-            type="text"
-            id="replace-input"
-            placeholder="替换..."
-            value={replaceText}
-            onChange={(e) => setReplaceText(e.target.value)}
-          />
-          <button className="replace-btn" onClick={handleReplaceCurrent} title="替换 (Ctrl+Shift+G)">替换</button>
-          <button className="replace-btn" onClick={handleReplaceAll} title="全部替换 (Ctrl+Shift+H)">全部</button>
-        </div>
-      )}
-    </div>
-  )
-}