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

internal/windows/media.go

@@ -1,4 +1,12 @@
 //go:build windows
+
+// ============================================================
+// WINDOWS-ONLY FILE — Windows media playback management.
+// Uses Win32 keybd_event to send VK_MEDIA_PLAY_PAUSE and a
+// PowerShell script to check media playback state via SMTC.
+// The Linux equivalent is internal/linux/media.go (playerctl)
+// ============================================================
+
 package windows
 
 import (

internal/windows/overlay.go

@@ -1,4 +1,12 @@
 //go:build windows
+
+// ============================================================
+// WINDOWS-ONLY FILE — Native Windows overlay window using
+// Win32 API directly (CreateWindowEx, GDI drawing, etc.).
+// This shows a pill-shaped overlay on screen during recording.
+// The Linux equivalent is internal/linux/overlay.go (no-op).
+// ============================================================
+
 package windows
 
 import (

internal/windows/process.go

@@ -1,4 +1,12 @@
 //go:build windows
+
+// ============================================================
+// WINDOWS-ONLY FILE — Windows process management utilities.
+// Uses Win32 API (OpenProcess, GetExitCodeProcess) to check
+// if a process is running. The Linux equivalent for process
+// checking is in internal/linux/process.go
+// ============================================================
+
 package windows
 
 import (

internal/windows/startup.go

@@ -1,4 +1,12 @@
 //go:build windows
+
+// ============================================================
+// WINDOWS-ONLY FILE — Windows startup (autostart) management
+// via the Windows Registry (HKCU\Software\Microsoft\Windows\
+// CurrentVersion\Run). The Linux equivalent for autostart
+// management is internal/linux/startup.go (XDG .desktop files)
+// ============================================================
+
 package windows
 
 import (