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/README.md

@@ -12,8 +12,9 @@ This README is for **developers** of the launcher. End-users see
 
 - **Host mode:** fetches the matching server binary from GitHub
   Releases for the user's picked Rec Room version, runs it as a
-  subprocess, opens a Cloudflare quick-tunnel, patches the user's
-  Rec Room install, hands the user a shareable join code.
+  subprocess and exposes it through a Localtunnel HTTPS URL (or
+  binds on the LAN if the user picked that mode), patches the
+  user's Rec Room install, hands the user a shareable join code.
 - **Join mode:** parses the join code, fetches the matching client
   patcher from GitHub Releases, patches the user's Rec Room install
   to point at the host.
@@ -34,7 +35,8 @@ launcher/
     ├── ReleaseDownloader.cs   GitHub Releases API + artifact unpack
     ├── ServerProcess.cs       Spawns the downloaded server binary
     ├── ClientPatcher.cs       Invokes install-plugin.ps1 from the unpacked patcher
-    ├── Tunnel.cs              Wraps `cloudflared tunnel --url …`
+    ├── LocaltunnelInstaller.cs Downloads the Localtunnel .NET client
+    ├── LocaltunnelTunnel.cs    Spawns the tunnel + parses the *.loca.lt URL
     ├── RecRoomPicker.cs       Microsoft.Win32.OpenFolderDialog
     └── JoinCode.cs            base64url-encoded {host, version, photonAppId, …}
 ```