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

internal/infrastructure/display/display.go

@@ -0,0 +1,25 @@
+// Package display exposes platform-specific helpers for reading the
+// geometry of the primary display, in both CSS (logical) and PHYSICAL
+// pixels. The overlay flow needs both: CSS pixels to size the Wails window
+// to "fullscreen" (since Wails uses CSS-px-equivalent units), and the
+// backing scale factor to translate the user's CSS-px selection rectangle
+// into the physical-pixel rectangle of the captured PNG.
+package display
+
+// Info describes the primary display.
+//
+// The struct is deliberately minimal: only the few fields the overlay flow
+// actually needs. We can grow it later without affecting callers because
+// it is returned by value.
+type Info struct {
+	// CSSWidth / CSSHeight are the logical dimensions of the primary
+	// display in points (i.e. what CSS / Wails uses).
+	CSSWidth  int
+	CSSHeight int
+
+	// Scale is backing factor (CSS-px → device-px). 2 on Retina, 1 on
+	// non-Retina. We model it as float64 to leave room for fractional
+	// scales (e.g. Linux 1.25×) even though macOS effectively only ever
+	// reports 1 or 2.
+	Scale float64
+}