refactor: TicketCreatePage用SchemaSidebar替换手写浏览器+SqlEditor暴露insertText光标定位

- SqlEditor: 添加 forwardRef + useImperativeHandle 暴露 insertText 方法
  - 支持在光标位置插入文本并移动光标
- TicketCreatePage: 删除300+行手写表结构/Redis/索引浏览代码
  - 统一使用 SchemaSidebar 组件（与查询页一致）
  - handleSchemaInsert: 已选库插table名,未选库插db.table名
  - 清理未用 imports/icons/types/helpers (RedisKeyItem, formatBytes等)
  - 848行 → 435行

frontend/src/components/SqlEditor.tsx

@@ -1,4 +1,4 @@
-import React, { useRef, useEffect, useCallback } from 'react';
+import React, { useRef, useEffect, useCallback, useImperativeHandle, forwardRef } from 'react';
 import { EditorState, Compartment } from '@codemirror/state';
 import type { Extension } from '@codemirror/state';
 import { EditorView, keymap, lineNumbers, placeholder as cmPlaceholder } from '@codemirror/view';
@@ -259,7 +259,12 @@ export function formatSQL(input: string): string {
 // SqlEditor component
 // ---------------------------------------------------------------------------
 
-const SqlEditor: React.FC<SqlEditorProps> = ({
+export interface SqlEditorHandle {
+  /** Insert text at cursor position and move cursor after inserted text */
+  insertText: (text: string) => void;
+}
+
+const SqlEditor = forwardRef<SqlEditorHandle, SqlEditorProps>(({
   value,
   onChange,
   placeholder = 'Enter SQL query…',
@@ -268,7 +273,7 @@ const SqlEditor: React.FC<SqlEditorProps> = ({
   readOnly = false,
   onExecute,
   schema,
-}) => {
+}, ref) => {
   const containerRef = useRef<HTMLDivElement>(null);
   const viewRef = useRef<EditorView | null>(null);
   const langCompartmentRef = useRef(new Compartment());
@@ -276,6 +281,20 @@ const SqlEditor: React.FC<SqlEditorProps> = ({
   const placeholderCompartmentRef = useRef(new Compartment());
   const isExternalUpdateRef = useRef(false);
 
+  // Expose insertText to parent via ref
+  useImperativeHandle(ref, () => ({
+    insertText: (text: string) => {
+      const view = viewRef.current;
+      if (!view) return;
+      const pos = view.state.selection.main.head;
+      view.dispatch({
+        changes: { from: pos, insert: text },
+        selection: { anchor: pos + text.length },
+      });
+      view.focus();
+    },
+  }), []);
+
   // Keep onChange in a stable ref so callbacks never go stale
   const onChangeRef = useRef(onChange);
   onChangeRef.current = onChange;
@@ -427,6 +446,6 @@ const SqlEditor: React.FC<SqlEditorProps> = ({
       className="sql-editor-wrapper"
     />
   );
-};
+});
 
 export default SqlEditor;