fix: Add cross-platform handling for tray, updater, and icon generation

- Add platform notes for tray startup, shortcut saving, and Linux-only settings
- Handle stat error in processRecording (missing file)
- Select correct binary name based on OS in updater
- Increase tray icon canvas size from 64 to 128 pixels
- Update frontend dist asset hash

linux_press_daemon.go

@@ -1,5 +1,12 @@
 //go:build linux
 
+// ============================================================
+// LINUX-ONLY FILE — Local HTTP daemon that receives hotkey
+// press/release pings from the GNOME custom shortcut helper.
+// This is the Linux equivalent of the Windows hotkey listener.
+// Any changes here will NOT affect the Windows build.
+// ============================================================
+
 package main
 
 import (