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/.

cli/DorkNet.ServerCli/DorkNet.ServerCli.csproj

@@ -49,6 +49,15 @@
     <Compile Include="..\..\launcher\Backend\TunneltoTunnel.cs">
       <Link>Backend\TunneltoTunnel.cs</Link>
     </Compile>
+    <Compile Include="..\..\launcher\Backend\TunneltoInstaller.cs">
+      <Link>Backend\TunneltoInstaller.cs</Link>
+    </Compile>
+    <Compile Include="..\..\launcher\Backend\LocaltunnelTunnel.cs">
+      <Link>Backend\LocaltunnelTunnel.cs</Link>
+    </Compile>
+    <Compile Include="..\..\launcher\Backend\LocaltunnelInstaller.cs">
+      <Link>Backend\LocaltunnelInstaller.cs</Link>
+    </Compile>
     <Compile Include="..\..\launcher\Backend\VersionsManifest.cs">
       <Link>Backend\VersionsManifest.cs</Link>
     </Compile>