refactor: restructure project to standard Go layout

- Reorganize code into cmd/bilidown and internal/ packages
- Rename client/ to web/ for frontend source
- Remove systray dependency for headless web service
- Embed static files into binary using go:embed
- Update import paths to use internal/ prefix
- Update .gitignore with common patterns

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/task/data.ts

@@ -0,0 +1,74 @@
+import { ResJSON } from "../mixin"
+import { TaskInDB, TaskStatus, VideoFormat } from "../work/type"
+
+let getActiveTaskController: AbortController | undefined
+
+export const getActiveTask = async (): Promise<ActiveTask[] | null> => {
+    getActiveTaskController?.abort()
+    getActiveTaskController = new AbortController()
+    try {
+        const res = await fetch('/api/getActiveTask', {
+            signal: getActiveTaskController.signal
+        }).then(res => res.json()) as ResJSON<ActiveTask[]>
+        if (!res.success) throw new Error(res.message)
+        return res.data
+    } catch (error) {
+        if (error instanceof Error && error.name === 'AbortError') return null
+        throw error
+    }
+}
+
+let getTaskListController: AbortController | undefined
+
+export const getTaskList = async (page: number, pageSize: number): Promise<TaskInDB[] | null> => {
+    getTaskListController?.abort()
+    getTaskListController = new AbortController()
+    try {
+        const res = await fetch(`/api/getTaskList?page=${page}&pageSize=${pageSize}`, {
+            signal: getTaskListController.signal
+        }).then(res => res.json()) as ResJSON<TaskInDB[]>
+        if (!res.success) throw new Error(res.message)
+        return res.data
+    } catch (error) {
+        if (error instanceof Error && error.name === 'AbortError') return null
+        throw error
+    }
+}
+
+export const showFile = async (path: string) => {
+    const res = await fetch(`/api/showFile?filePath=${encodeURIComponent(path)}`).then(res => res.json()) as ResJSON
+    if (!res.success) throw new Error(res.message)
+}
+
+/** 用于刷新任务实时进度 */
+type ActiveTask = {
+    bvid: string
+    cid: number
+    /** 分辨率代码 */
+    format: VideoFormat
+    /** 视频标题 */
+    title: string
+    /** 视频发布者 */
+    owner: string
+    /** 视频封面 */
+    cover: string
+    /** 任务进度 */
+    status: TaskStatus
+    /** 文件保存到的目录 */
+    folder: string
+    /** 任务 ID */
+    id: number
+    /** 音频文件下载进度 */
+    audioProgress: number
+    /** 视频文件下载进度 */
+    videoProgress: number
+    /** 音视频合并进度 */
+    mergeProgress: number
+    /** 视频时长，秒 */
+    duration: number
+}
+
+export const deleteTask = async (id: number) => {
+    const res = await fetch(`/api/deleteTask?id=${id}`).then(res => res.json()) as ResJSON
+    if (!res.success) throw new Error(res.message)
+}