feat!: genesis-pinned operator set, server identity with an encrypted control link, key-less join codes; release key continuity

Join codes need no passkey touch and carry only public values (genesis
fingerprint, owner credentials, installer hashes). Nodes pin the genesis and
owners at enrollment and only follow passkey-signed operator set versions.
The panel's server key is listed in the set; pinned nodes require its
signature and run the control link under AES-256-GCM. Password sessions carry
no capabilities. The updater adopts a next_key from a signed manifest.

Bump version to 0.2.0. [CI SKIP]

backend/shared/MoShiro.Protocol/Rpc/MoShiroRpc.cs

@@ -152,10 +152,6 @@ public sealed class AgentEndpoint
     /// <summary>Agent 面向 Probe 的 TLS 证书公钥（SPKI，base64）：证书按它的 SHA-256 指纹固定，敲门密钥由它和 Probe 的身份密钥派生。</summary>
     [JsonPropertyName("public_key")]
     public string PublicKey { get; set; } = "";
-
-    /// <summary>操作员批准这个 Agent 的证明；固定了创世的 Probe 没有它就不连。</summary>
-    [JsonPropertyName("proof")]
-    public MemberProofDto? Proof { get; set; }
 }
 
 /// <summary>期望状态文档（Fleet state type = <c>probe_agents</c>）：Backend 直接下发给每个 Probe 的 Agent 列表。</summary>