重构：Wails v3 迁移 + 前端目录规范化 + Sidebar滚动优化

- web/ → frontend/ 目录重命名（Wails v3 标准结构）
- main.go: Middleware 修复 custom.js 404 + DevTools 延迟启动
- Sidebar: 收藏夹内部独立滚动 + 帮助区块固定底部
- useFavorites.ts: longPressTimer const→let 修复 TypeError
- App.vue: Arco Tabs padding-top 覆盖
- build: config.yml / Taskfile.yml 对齐官方模板，devtools build tag
- 新增 v3 bindings、vite.config.js、跨平台构建配置

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

build/appicon.icon/Assets/wails_icon_vector.svg

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<svg width="100%" height="100%" viewBox="0 0 583 533" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xml:space="preserve" xmlns:serif="http://www.serif.com/" style="fill-rule:evenodd;clip-rule:evenodd;stroke-linejoin:round;stroke-miterlimit:2;">
+    <g transform="matrix(1,0,0,1,-246,-251)">
+        <g id="Ebene1">
+            <path d="M246,251L265,784L401,784L506,450L507,450L505,784L641,784L829,251L682,251L596,567L595,567L596,251L478,251L378,568L391,251L246,251Z"/>
+        </g>
+    </g>
+</svg>

build/appicon.icon/icon.json

@@ -0,0 +1,51 @@
+{
+  "fill" : {
+    "automatic-gradient" : "extended-gray:1.00000,1.00000"
+  },
+  "groups" : [
+    {
+      "layers" : [
+        {
+          "fill-specializations" : [
+            {
+              "appearance" : "dark",
+              "value" : {
+                "solid" : "srgb:0.92143,0.92145,0.92144,1.00000"
+              }
+            },
+            {
+              "appearance" : "tinted",
+              "value" : {
+                "solid" : "srgb:0.83742,0.83744,0.83743,1.00000"
+              }
+            }
+          ],
+          "image-name" : "wails_icon_vector.svg",
+          "name" : "wails_icon_vector",
+          "position" : {
+            "scale" : 1.25,
+            "translation-in-points" : [
+              36.890625,
+              4.96875
+            ]
+          }
+        }
+      ],
+      "shadow" : {
+        "kind" : "neutral",
+        "opacity" : 0.5
+      },
+      "specular" : true,
+      "translucency" : {
+        "enabled" : true,
+        "value" : 0.5
+      }
+    }
+  ],
+  "supported-platforms" : {
+    "circles" : [
+      "watchOS"
+    ],
+    "squares" : "shared"
+  }
+}