Make install_server handle one-time admin bootstrap prompt

deploy/README.md

@@ -38,6 +38,7 @@ This creates:
 - `/home/bestmidi/chgrid/server/.venv`
 - `/home/bestmidi/chgrid/server/config.toml` (if missing)
 - `/home/bestmidi/chgrid/server/.env` with `CHGRID_AUTH_SECRET` (if missing)
+- On first run only, if no admin exists, it prompts to create one immediately.
 
 Edit `/home/bestmidi/chgrid/server/config.toml`:
 - `server.bind_ip = "127.0.0.1"`
@@ -48,6 +49,14 @@ Edit `/home/bestmidi/chgrid/server/config.toml`:
 - `storage.state_file = "runtime/items.json"`
 - `auth.db_file = "runtime/chatgrid.db"`
 
+If you skip first-run admin creation, run later:
+
+```bash
+cd /home/bestmidi/chgrid/server
+source .env
+.venv/bin/python main.py --config config.toml --bootstrap-admin
+```
+
 ## 4) Build and publish client
 
 ```bash