feat(app): implement basic function

General
- 配置界面支持配置对象存储桶
- 快捷键进入截图
- 一键上传截图 & 复制截图链接

MacOS
- 状态栏指示器和应用图标

flush_frame.go

@@ -0,0 +1,14 @@
+// flush_frame.go provides a tiny helper that yields the current goroutine
+// long enough for the OS compositor to redraw after WindowHide / Unfullscreen.
+//
+// Without this, the screenshot can include the just-hidden overlay window
+// because Cocoa hasn't redrawn yet by the time we ask for the pixels.
+package main
+
+import "time"
+
+func flushFrame() {
+	// 80ms is empirically enough on Apple Silicon at 120Hz; on slower devices
+	// the worst case is a single redraw delay, still imperceptible to the user.
+	time.Sleep(80 * time.Millisecond)
+}