Modernize the Windows installer, tray and runtime control; fix lifecycle bugs.

Installer: dynamic light/dark Win11 style, new brand wizard images, auto
language, exclusive run mode (tray / Windows service) plus autostart and
auto-update on the Tasks page (pre-selected from what is installed on
upgrades, untouched by silent updates), 5 localized Start Menu entries.

Tray: theme-aware rounded menu with live status, icons and status-dot tray
icon; health polled off the UI thread; Settings submenu toggles autostart
and daily updates; browser opened de-elevated via explorer.

Fixes:
- tray Stop/Start was ignored in service mode (service_run restarted the
  children) - all start/stop now goes through runtime_ctl.ps1
- logon tray task and SYSTEM service task were killed after 72h (default
  ExecutionTimeLimit); autostart was registered for the elevating account
  and opened a browser on every logon
- uninstall left the NetXTray/NetXUpdate tasks behind
- silent auto-update killed the tray without restarting it
- repair_venv.ps1 was never staged into the release
- wildcard NETX_HOST (0.0.0.0) broke health checks
- ICO frames were PNG, which System.Drawing decodes as noise; icons now
  use the current brand mark

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packaging/install_service.ps1

@@ -129,7 +129,9 @@ if ($Mode -eq "winsw") {
     $action = New-ScheduledTaskAction -Execute "powershell.exe" -Argument $arg -WorkingDirectory $prog
     $trigger = New-ScheduledTaskTrigger -AtStartup
     $principal = New-ScheduledTaskPrincipal -UserId "SYSTEM" -LogonType ServiceAccount -RunLevel Highest
-    $settings = New-ScheduledTaskSettingsSet -AllowStartIfOnBatteries -DontStopIfGoingOnBatteries -RestartCount 3 -RestartInterval (New-TimeSpan -Minutes 1)
+    # ExecutionTimeLimit 0: the default (72h) would kill the long-running supervisor.
+    $settings = New-ScheduledTaskSettingsSet -AllowStartIfOnBatteries -DontStopIfGoingOnBatteries -RestartCount 3 -RestartInterval (New-TimeSpan -Minutes 1) `
+        -ExecutionTimeLimit ([TimeSpan]::Zero)
     Register-ScheduledTask -TaskName "NetXService" -TaskPath "\NetX\" -Action $action -Trigger $trigger -Principal $principal -Settings $settings -Force | Out-Null
     if ($Start) {
         Start-ScheduledTask -TaskName "NetXService" -TaskPath "\NetX\"