🔧 fix(app-window): 修复 Linux Mint 窗口仅左上角可缩放问题

- 增加 Linux 运行时识别并启用专用缩放命中层
- 补齐四边四角 app-region: drag 热区
- Linux 下禁用外层 clipPath 裁切以避免边缘命中异常

frontend/src/App.tsx

@@ -2,7 +2,7 @@ import React, { useState, useEffect } from 'react';
 import { Layout, Button, ConfigProvider, theme, Dropdown, MenuProps, message, Modal, Spin, Slider, Progress } from 'antd';
 import zhCN from 'antd/locale/zh_CN';
 import { PlusOutlined, BulbOutlined, BulbFilled, ConsoleSqlOutlined, UploadOutlined, DownloadOutlined, CloudDownloadOutlined, BugOutlined, ToolOutlined, InfoCircleOutlined, GithubOutlined, SkinOutlined, CheckOutlined, MinusOutlined, BorderOutlined, CloseOutlined, SettingOutlined } from '@ant-design/icons';
-import { EventsOn } from '../wailsjs/runtime/runtime';
+import { Environment, EventsOn } from '../wailsjs/runtime/runtime';
 import Sidebar from './components/Sidebar';
 import TabManager from './components/TabManager';
 import ConnectionModal from './components/ConnectionModal';
@@ -29,6 +29,7 @@ function App() {
   const effectiveBlur = normalizeBlurForPlatform(appearance.blur);
   const blurFilter = blurToFilter(effectiveBlur);
   const windowCornerRadius = 14;
+  const [isLinuxRuntime, setIsLinuxRuntime] = useState(false);
 
   // 同步 macOS 窗口透明度：opacity=1.0 且 blur=0 时关闭 NSVisualEffectView，
   // 避免 GPU 持续计算窗口背后的模糊合成
@@ -36,6 +37,23 @@ function App() {
     SetWindowTranslucency(appearance.opacity, appearance.blur).catch(() => {});
   }, [appearance.opacity, appearance.blur]);
 
+  useEffect(() => {
+      let cancelled = false;
+      Environment()
+          .then((env) => {
+              if (cancelled) return;
+              setIsLinuxRuntime((env?.platform || '').toLowerCase() === 'linux');
+          })
+          .catch(() => {
+              if (cancelled) return;
+              const platform = typeof navigator !== 'undefined' ? navigator.platform : '';
+              setIsLinuxRuntime(/linux/i.test(platform));
+          });
+      return () => {
+          cancelled = true;
+      };
+  }, []);
+
   // Background Helper
   const getBg = (darkHex: string, lightHex: string) => {
       if (!darkMode) return `rgba(255, 255, 255, ${effectiveOpacity})`; // Light mode usually white
@@ -550,6 +568,17 @@ function App() {
       };
   }, []);
 
+  const linuxResizeHandleStyleBase = {
+      position: 'fixed',
+      zIndex: 12000,
+      background: 'transparent',
+      WebkitAppRegion: 'drag',
+      '--wails-draggable': 'drag',
+      userSelect: 'none'
+  } as any;
+
+  const showLinuxResizeHandles = isLinuxRuntime;
+
   return (
     <ConfigProvider
         locale={zhCN}
@@ -593,8 +622,8 @@ function App() {
             display: 'flex', 
             flexDirection: 'column',
             background: 'transparent',
-            borderRadius: windowCornerRadius,
-            clipPath: `inset(0 round ${windowCornerRadius}px)`,
+            borderRadius: showLinuxResizeHandles ? 0 : windowCornerRadius,
+            clipPath: showLinuxResizeHandles ? 'none' : `inset(0 round ${windowCornerRadius}px)`,
             backdropFilter: blurFilter,
             WebkitBackdropFilter: blurFilter,
         }}>
@@ -891,6 +920,21 @@ function App() {
                   ) : null}
               </div>
           </Modal>
+
+          {showLinuxResizeHandles && (
+              <>
+                  {/* Linux Mint 下 frameless 仅局部可缩放：补四边四角命中层 */}
+                  <div style={{ ...linuxResizeHandleStyleBase, top: 0, left: 14, right: 14, height: 6, cursor: 'ns-resize' }} />
+                  <div style={{ ...linuxResizeHandleStyleBase, bottom: 0, left: 14, right: 14, height: 6, cursor: 'ns-resize' }} />
+                  <div style={{ ...linuxResizeHandleStyleBase, top: 14, bottom: 14, left: 0, width: 6, cursor: 'ew-resize' }} />
+                  <div style={{ ...linuxResizeHandleStyleBase, top: 14, bottom: 14, right: 0, width: 6, cursor: 'ew-resize' }} />
+
+                  <div style={{ ...linuxResizeHandleStyleBase, top: 0, left: 0, width: 14, height: 14, cursor: 'nwse-resize' }} />
+                  <div style={{ ...linuxResizeHandleStyleBase, top: 0, right: 0, width: 14, height: 14, cursor: 'nesw-resize' }} />
+                  <div style={{ ...linuxResizeHandleStyleBase, bottom: 0, left: 0, width: 14, height: 14, cursor: 'nesw-resize' }} />
+                  <div style={{ ...linuxResizeHandleStyleBase, bottom: 0, right: 0, width: 14, height: 14, cursor: 'nwse-resize' }} />
+              </>
+          )}
           
           {/* Ghost Resize Line for Sidebar */}
           <div