Remove auto-start: launcher owns the app lifecycle

The TeslaConsole launcher starts and stops RIOJoy, so the app no longer
registers any auto-start entry:
- install-rio.ps1: drop the HKLM ...\Run registration and the post-install
  launch (and the -NoLaunch param).
- Tray: remove the "Start with Windows" menu item and delete AutoStartManager
  (HKCU ...\Run writer).
- AppConfig: drop the now-inert AutoStart field (+ test).
- Docs (PLAN.md, README-DEPLOY.txt) updated to reflect launcher-managed start/stop.

uninstall-rio.ps1 still clears any leftover Run entry from older auto-starting
builds. Solution builds; 241 tests pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/RioJoy.Core/Profiles/AppConfig.cs

@@ -29,9 +29,6 @@ public sealed class AppConfig
     /// </summary>
     public string? NeutralProfileName { get; set; }
 
-    /// <summary>Start RIOJoy with Windows.</summary>
-    public bool AutoStart { get; set; }
-
     /// <summary>
     /// Path to the cockpit overlay template (<c>regions.json</c>) used to generate
     /// per-profile wallpapers (Phase 7). Null disables wallpaper generation. The