Localtunnel hosting + admin panel + AppData db

- Default hosting mode is now Localtunnel — public *.loca.lt URL,
  no account, auto-fetched on first run. Replaces the prototyped
  Tailscale mode.
- Tailscale code purged from launcher + CLI; docs swapped to
  Localtunnel throughout (easy-setup, joining-a-server, server-cli,
  troubleshooting, faq, READMEs).
- Launcher sidebar gains an Open admin panel button — opens
  https://admin.<apex> in the browser once the server is live.
- SQLite db moves to %APPDATA%\DorkNet\dorknet.db (server reads
  Database__SqlitePath env var, launcher passes it). Existing dbs
  under <serverDir>\data\ are migrated on first run.
- CLI Program.cs: --mode default flips from tailscale to localtunnel;
  csproj links in LocaltunnelTunnel + LocaltunnelInstaller.
- New Backend files: LauncherNameServer, LocaltunnelInstaller,
  LocaltunnelTunnel, SingleOriginServiceMap.
- .gitignore: exclude installer/out/.

launcher/Backend/StartupStep.cs

@@ -77,9 +77,13 @@ public static class StartupFlow
         new StartupStep("Download server binary"),
         new StartupStep(mode switch
         {
+            HostingMode.SingleOriginTunnel => "Start localtunnel",
             HostingMode.LocalNetwork => "Set up local sslip.io address",
-            HostingMode.RemoteWildcard => "Set up Tunnelto tunnel",
-            _ => "Set up Tunnelto tunnel",
+            HostingMode.RemoteWildcard => "Install / start Tunnelto tunnel",
+            // Internet maps onto SingleOriginTunnel via AppState.Load
+            // migration; keep the arm in case a stale value sneaks in.
+            HostingMode.Internet => "Start localtunnel",
+            _ => "Start localtunnel",
         }),
         new StartupStep("Start the server"),
         new StartupStep("Download client patcher"),