agent: unify listening and dialing with directed mutual measurements

Replace Probe with Agent across node runtime, Fleet contracts, backend state, API and storage. Report incoming sessions and outgoing link health through each Agent uplink, and retain directed link controls and retry.

Update protocol fixtures and end-to-end coverage for the unified model; accept requested cancellation during the Fleet timeout test cleanup.

backend/shared/MoShiro.Protocol/Raw/RawChunkCodec.cs

@@ -6,7 +6,7 @@ using Fleet.Core;
 namespace MoShiro.Protocol;
 
 /// <summary>
-/// RawChunk 的编解码（Probe、Agent、Backend、离线工具共用同一份代码）。
+/// RawChunk 的编解码（拨号方、Agent、Backend、离线工具共用同一份代码）。
 /// 布局：<c>"MSRC" | u8 container_version | u32 crc32c(压缩数据) | Brotli( u32 header_len | header JSON | 各列数据 )</c>。
 /// 列数据：可空列先写有效位图，再写有效值；plain 为无符号 varint（有符号类型用 zigzag），delta 为与上一个有效值之差的 zigzag varint。
 /// </summary>
@@ -334,16 +334,16 @@ public static class RawChunkCodec
 
     private static string? RoleName(ColumnRole role) => role switch
     {
-        ColumnRole.TsProbe => "ts_probe",
-        ColumnRole.TsAgent => "ts_agent",
+        ColumnRole.TsDialer => "ts_dialer",
+        ColumnRole.TsListener => "ts_listener",
         ColumnRole.TsLocal => "ts_local",
         _ => null,
     };
 
     private static ColumnRole ParseRole(string? text) => text switch
     {
-        "ts_probe" => ColumnRole.TsProbe,
-        "ts_agent" => ColumnRole.TsAgent,
+        "ts_dialer" => ColumnRole.TsDialer,
+        "ts_listener" => ColumnRole.TsListener,
         "ts_local" => ColumnRole.TsLocal,
         _ => ColumnRole.None,
     };