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/src/MoShiro.Backend.Application/Agents/LinkService.cs

@@ -0,0 +1,68 @@
+namespace MoShiro.Backend.Application;
+
+/// <summary>某一时刻的「线路」开关：自动连接的总开关，加上每一对（Probe，Agent）的手动设置。</summary>
+public sealed class LinkSnapshot
+{
+    private readonly Dictionary<(string Probe, string Agent), bool> _overrides;
+
+    public LinkSnapshot(bool auto, Dictionary<(string Probe, string Agent), bool> overrides)
+    {
+        Auto = auto;
+        _overrides = overrides;
+    }
+
+    /// <summary>自动连接：开着时，没有手动设置的 Probe 和 Agent 都会连；关着时，只有手动开启的才连。</summary>
+    public bool Auto { get; }
+
+    /// <summary>手动设置：<c>true</c> 强制连、<c>false</c> 强制不连、<c>null</c> 没设置（跟随自动连接）。</summary>
+    public bool? OverrideOf(string probeId, string agentId) => _overrides.TryGetValue((probeId, agentId), out bool value) ? value : null;
+
+    /// <summary>这一对最终连不连：手动设置优先，没有就看自动连接。</summary>
+    public bool IsLinked(string probeId, string agentId) => OverrideOf(probeId, agentId) ?? Auto;
+}
+
+/// <summary>
+/// 哪些（Probe，Agent）要连成线路。由面板决定、Probe 主动拨出：自动连接开着时所有 Probe 和 Agent 两两连（默认），
+/// 关着时只连手动选中的；每一对还可以手动强制开或关。手动设置存在设置表里（<c>link.&lt;probe&gt;.&lt;agent&gt;</c>，值 1 或 0，空表示没设置）。
+/// 判断结果分别用在 Probe 的 Agent 列表、Agent 允许的 Probe（<c>peers</c>）和线路目录里；改动之后要调用 <see cref="AgentService.AfterAgentSetChangedAsync"/> 重新下发。
+/// </summary>
+public sealed class LinkService
+{
+    private const string Prefix = "link.";
+
+    private readonly ISettingsStore _settings;
+
+    public LinkService(ISettingsStore settings)
+    {
+        _settings = settings;
+    }
+
+    public async ValueTask<LinkSnapshot> SnapshotAsync(CancellationToken ct)
+    {
+        IReadOnlyDictionary<string, string> all = await _settings.GetAllAsync(ct);
+        var overrides = new Dictionary<(string, string), bool>();
+        foreach ((string key, string value) in all)
+        {
+            string[] parts = key.Split('.');
+            if (parts.Length == 3 && parts[0] + "." == Prefix && value is "1" or "0")
+            {
+                overrides[(parts[1], parts[2])] = value == "1";
+            }
+        }
+
+        return new LinkSnapshot(all.GetValueOrDefault(SettingsService.AutoLink) != "false", overrides);
+    }
+
+    /// <summary>手动设置一对线路：<c>true</c> 强制连、<c>false</c> 强制不连、<c>null</c> 取消手动设置。</summary>
+    public ValueTask SetAsync(string probeId, string agentId, bool? enabled, CancellationToken ct) =>
+        _settings.SetAsync($"{Prefix}{probeId}.{agentId}", enabled is null ? "" : enabled.Value ? "1" : "0", ct);
+
+    /// <summary>Probe 或 Agent 被删除：清掉所有涉及它的手动设置。</summary>
+    public async ValueTask ForgetNodeAsync(string nodeId, CancellationToken ct)
+    {
+        foreach (string key in (await _settings.GetAllAsync(ct)).Keys.Where(k => k.StartsWith(Prefix, StringComparison.Ordinal) && k.Split('.').Skip(1).Contains(nodeId)))
+        {
+            await _settings.SetAsync(key, "", ct);
+        }
+    }
+}