feat(bridge): server id from the environment, and the first release workflow (phase 18)

Module-rust phase 18, step 3 of docs/modules/rust/PLAN.md §34.2.7.

The environment seam (D150): when the plugin writes its default config and
RUSTLINK_SERVER_ID holds a valid id (the site's ^[a-z0-9][a-z0-9-]{0,63}$),
the file's ServerId is that value. It is read nowhere else: after that write
the file is canonical and the site's lock applies. An invalid value is logged
and ignored. This is how the egg names a server; not a message change, so the
protocol stays at 12.

The release (D145, §34.2.1): release.yml reuses servuo-plugins' release engine
unchanged (tag-only, secrets preflighted, orphan tags recovered and swept, the
installer's bundle.yml dispatched at the end). The adapter re-runs
checkPlugin.js and packages runicgateway-rust-plugin-<version>.tar.gz with a
framework-neutral layout: RunicGateway.cs, its [Info] version stamped to the
release, and a manifest.json folding in overlay.toml.

overlay.toml gains min_carbon_version = "2.0.259", the build R19 was proven on.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

overlay/oxide/plugins/RunicGateway.cs

@@ -413,9 +413,47 @@ namespace Oxide.Plugins
             public int MapMaxBases = MapDefaultMax;
         }
 
+        /// <summary>
+        ///     Runs only when this plugin has no config file yet — so it is the one moment a server id
+        ///     can arrive from outside the file (D150). A Pterodactyl egg cannot write a framework's
+        ///     config directory (Carbon lets an operator move it), but it can set an environment
+        ///     variable, and `RUSTLINK_SERVER_ID` is the one the sidecar already reads for its
+        ///     cross-check. After this write the file is canonical and the website's lock applies,
+        ///     so changing the variable later changes nothing — which is what keeps a server's
+        ///     history attached to one id.
+        /// </summary>
         protected override void LoadDefaultConfig()
         {
-            Config.WriteObject(new PluginConfig(), true);
+            var config = new PluginConfig();
+
+            string fromEnv = Environment.GetEnvironmentVariable("RUSTLINK_SERVER_ID");
+            if (!string.IsNullOrEmpty(fromEnv))
+            {
+                if (IsValidServerId(fromEnv))
+                    config.ServerId = fromEnv;
+                else
+                    PrintWarning($"RUSTLINK_SERVER_ID '{fromEnv}' is not a valid server id " +
+                                 $"(lowercase letters, digits and '-', 1-64, not starting with '-'); " +
+                                 $"the new config keeps '{config.ServerId}'");
+            }
+
+            Config.WriteObject(config, true);
+        }
+
+        /// <summary>The website's rule for a server id, `^[a-z0-9][a-z0-9-]{0,63}$`, without a Regex.</summary>
+        private static bool IsValidServerId(string id)
+        {
+            if (string.IsNullOrEmpty(id) || id.Length > 64 || id[0] == '-')
+                return false;
+
+            foreach (char c in id)
+            {
+                bool ok = (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') || c == '-';
+                if (!ok)
+                    return false;
+            }
+
+            return true;
         }
 
         private void LoadConfigValues()