Update check: version feed from the git server's releases, title-screen banner, clearer version refusals

docs/HOSTING.md

@@ -76,6 +76,7 @@ the ones you'll want first:
 | `difficulty` | normal | easy / normal / hard |
 | `sleep` | all_online | or `half`, `anyone`, `off` |
 | `backups_kept`, `backup_hours` | 10, 6 | see below |
+| `check_updates` | true | at start-up, say in the log if a newer Emberwild is out (and whether its protocol differs, so new players couldn't join) |
 | `allowlist`, `banned`, `admins` | | player ids (use `/ban`, `/admin` rather than editing) |
 
 ## Backups

docs/ROADMAP.md

@@ -100,6 +100,26 @@ phases M2.0-M2.7).
 Needed because every network change bumps the protocol (12 as of P5), and
 an out-of-date game can't join an up-to-date server: today that means
 `git pull` and a restart on every machine.
+
+*Built so far (the check):* `scripts/core/updates.gd` asks the feed in
+Project Settings (`emberwild/updates/feed`, now the git server's
+`releases/latest` API; Gitea, Forgejo and GitHub answer alike) once at
+start-up. It reads the release's `version.json` asset (written by
+`tools/export.sh`: version, protocol, per-platform file, sha256 and size).
+The title screen shows the version bottom left and, when a newer one is
+out, a card with its notes and **Download** (this platform's zip, or the
+release page). A "Different game version" refusal now names the server's
+version and protocol and says whether you or the server needs updating;
+a dedicated server says in its log when it's behind (`check_updates` in
+server.json). Pause menu: **Check for updates at start**. Tests and bots
+never touch the network. Still to do: downloading, verifying and
+swapping it in (below).
+
+**To publish a release:** bump `config/version` in project.godot and the
+four version numbers in export_presets.cfg, run
+`NOTES="..." tools/export.sh`, and make a release on the git server (tag
+`v<version>`) with the two zips and build/version.json attached. The repo
+(or at least its releases) must be readable without logging in.
 - **Knowing there's an update:** the game checks a small version file
   (version number, protocol, per-platform download URLs and checksums) at
   start-up and from the title screen. The server checks too. When joining