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/.

README.md

@@ -39,9 +39,9 @@ One download, two flavours: an **installer** (Start menu shortcut +
 rolling auto-updates) or a **portable `dorknet.exe`** (drop anywhere).
 Pick a Rec Room build on first launch, host or join.
 
-- **Host a server** — runs a local server + Tunnelto tunnel for the
-  client version you pick, patches your Rec Room install, and gives
-  you a shareable join code.
+- **Host a server** — runs a local server, opens a free Localtunnel
+  HTTPS URL for it (no account), patches your Rec Room install for the
+  client version you pick, and gives you a shareable join code.
 - **Join a server** — paste the code, point at your Rec Room install,
   hit play. The launcher fetches the matching patcher.