feat: bind each node to the binary it runs at its first handshake; refuse changes that are not in a CI-signed manifest [CI]

backend/src/MoShiro.Backend.Api/EmbeddedReleaseKey.cs

@@ -0,0 +1,9 @@
+using MoShiro.Backend.Application;
+
+namespace MoShiro.Backend.Api;
+
+/// <summary>内嵌在程序里的 CI 发布公钥（<c>packaging/update/release-key.pub.pem</c>）。</summary>
+public sealed class EmbeddedReleaseKey : IReleaseKey
+{
+    public string Pem => InstallScripts.ReleaseKey();
+}