The SVG-derived tray icons + multi-resolution .ico path looked correct on
disk but Wails3's Shell_NotifyIcon update never landed on the running
Windows tray — the icon stayed frozen on the .exe resource regardless of
how many times we called SetIcon. Single-PNG fed through the same path
updates correctly, so revert to the source-of-truth PNGs that ship with
the legacy Fyne UI and remove the icons_windows.go / tray_icon_*.go
split. The 6 colored tray PNGs and 6 macOS-template PNGs come from
client/ui/assets verbatim. Generation pipeline (assets/svg/) is gone.