Auto-detected dark vs light tray glyph fails on GNOME, whose top bar
is permanently dark even when the system color scheme is light, so
the dark glyph disappears against it. Add a persisted user override
("auto" / "light" / "dark") that the SNI tray respects at startup
and on the fly.
Backend pieces:
- TraySettings gains tray_icon_theme: String with "auto" default and
a normalize_tray_icon_theme() helper that clamps unknown values
back to "auto". SQLite migration ALTERs the table to add the
column when an older DB is opened.
- tray_linux_ksni::decode_tray_icons takes an optional override and
resolve_dark_tray() consults it before falling back to the
existing GNOME/GTK/KDE auto-detection. init() forwards it.
- LinuxTrayHandle gains set_icon_theme(theme); a new
TrayUpdate::SetIconTheme variant flows through the dedicated
worker thread so re-decoding plus handle.update() happen outside
the tokio runtime (same panic-avoidance pattern used for
tooltip updates).
- v2_set_tray_icon_theme persists the value, mirrors it to the
global startup store, and pushes it to the live tray handle so
the icon flips without restart.
cc
vicrodh
ee713e3f0c