ci: version from the tag or the commits since it; dev images from main gated on tests; recognise -dev. tags [CI SKIP]

backend/src/MoShiro.Backend.Application/Updates/BackendUpdates.cs

@@ -55,9 +55,14 @@ public sealed class BackendUpdates : IHostedService
             return "release";
         }
 
-        return BuildInfo.Tag is { } tag && (tag.StartsWith("dev-", StringComparison.Ordinal) || tag.StartsWith("main-", StringComparison.Ordinal)) ? "dev" : "release";
+        return IsDevTag(BuildInfo.Tag) ? "dev" : "release";
     }
 
+    /// <summary>开发构建的 tag：新格式 v0.4.1-dev.12-abc1234（含 -dev.），以及旧的 dev-&lt;sha&gt;、main-&lt;sha&gt;。</summary>
+    public static bool IsDevTag(string? tag) =>
+        tag is not null
+        && (tag.Contains("-dev.", StringComparison.Ordinal) || tag.StartsWith("dev-", StringComparison.Ordinal) || tag.StartsWith("main-", StringComparison.Ordinal));
+
     public async ValueTask<BackendUpdateView> GetAsync(CancellationToken ct)
     {
         string channel = ChannelOf(_options);