refactor!: rename the project from Monitor to MoShiro [CI]

Namespaces, assemblies, solution, binaries, images, systemd units, config paths, environment variables, protocol methods and the Linux user are all renamed. Breaking: existing databases, node identities and installed units must be recreated.

backend/fleet/src/Fleet.Core/StringId.cs

@@ -3,7 +3,7 @@ using System.Text.Json.Serialization;
 
 namespace Fleet.Core;
 
-/// <summary>节点 ID（带类型前缀的 ULID）。Monitor 中的 AgentId 就是 NodeId。</summary>
+/// <summary>节点 ID（带类型前缀的 ULID）。MoShiro 中的 AgentId 就是 NodeId。</summary>
 [JsonConverter(typeof(NodeIdJsonConverter))]
 public readonly record struct NodeId(string Value)
 {