feat: add automation features (auto-update, auto-start, scheduled updates)

README.md

@@ -50,6 +50,61 @@ All paths are configurable via environment variables:
 | `FRONTEND_DIR` | `../frontend/dist` | Built frontend assets |
 | `LISTEN` | `:8080` | HTTP listen address |
 
+## Automation
+
+The panel can perform automatic operations at startup and on a schedule.
+
+### Startup tasks
+
+Configured in the **Automation** section of the Settings UI:
+
+| Setting | Description |
+|---------|-------------|
+| **Auto-update server on startup** | Runs `steamcmd +app_update` for the Arma 3 server binary when the web service starts. |
+| **Auto-update mods on startup** | Downloads workshop updates for every enabled mod in the active modlist when the web service starts. |
+| **Auto-start server on startup** | Restarts the game server if it was running when the web service last stopped. Useful for recovery after host backup cycles or container restarts. |
+
+All startup tasks run asynchronously — the web UI is available immediately.
+
+### Scheduled updates
+
+Set a **cron expression** in the `Scheduled Update` field to run game + mod updates on a recurring schedule (e.g. `"0 4 * * *"` for daily at 4 AM). Leave empty to disable.
+
+The scheduled update runs even if the game server is currently running.
+
+## SteamCMD Authentication
+
+The panel integrates with SteamCMD for server binary updates and workshop mod downloads.
+
+### Anonymous (default)
+
+The `Steam User` field in the settings UI defaults to `anonymous`.  
+In this mode, **no Steam account is required** — SteamCMD uses `+login anonymous`.
+
+- Workshop mod downloads always use this mode, regardless of the configured user.
+- The Arma 3 server binary update is available via `+login anonymous` only if the server files are publicly accessible on that Steam account.
+
+### Authenticated login
+
+To update the Arma 3 server binary (`app_update 233780`) with a real Steam account, set the `Steam User` field to your account name.
+
+The web panel does not pass a password — SteamCMD relies on a **cached session**.  
+You must authenticate manually once so the login token is persisted:
+
+```bash
+# Docker
+docker exec -it arma3-web steamcmd +login your_steam_username
+```
+
+Enter your password when prompted, including any Steam Guard code if enabled. The session is cached inside the container's filesystem (`~/.steam/`).
+
+> **Note:** SteamCMD sessions may expire. Re-run the login command if the "Update Server" button fails with an authentication error.
+
+### Security
+
+- Steam credentials saved in `data/settings.json` are stored as **plain text**.
+- It is recommended to use a **dedicated Steam account** with only the necessary game licenses for automated server management.
+
 ## API
 
 REST API at `/api/*` and WebSocket endpoints at `/ws/*`. Key routes: