refactor(ui): remove the stale-worker banner

The banner compared the running worker's build SHA against the
selected list's HEAD via a git ancestor check on every list switch
and reconnect. It added a git-rev-parse MSBuild target, a hub call,
and a poll loop for a corner case that hasn't come up in practice —
not worth the moving parts.

src/ClaudeDo.Worker/ClaudeDo.Worker.csproj

@@ -35,18 +35,4 @@
     <InternalsVisibleTo Include="ClaudeDo.Worker.Tests" />
   </ItemGroup>
 
-  <!-- Stamps this worker's exact commit into AssemblyInformationalVersion as "+{sha}" so a
-       running instance can report which commit it was built from (see WorkerHub.GetWorkerBuildInfo).
-       Independent of MinVer: MinVerVersionOverride (release builds) replaces the base version but
-       doesn't touch SourceRevisionId, and the SDK appends it to InformationalVersion regardless. -->
-  <Target Name="SetBuildRevisionFromGit" BeforeTargets="GetAssemblyVersion" Condition="'$(SourceRevisionId)' == ''">
-    <Exec Command="git rev-parse HEAD"
-          WorkingDirectory="$(MSBuildProjectDirectory)"
-          ConsoleToMSBuild="true"
-          StandardOutputImportance="low"
-          ContinueOnError="WarnAndContinue">
-      <Output TaskParameter="ConsoleOutput" PropertyName="SourceRevisionId" />
-    </Exec>
-  </Target>
-
 </Project>

src/ClaudeDo.Worker/Hub/WorkerHub.cs

@@ -35,20 +35,6 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
     private static readonly string Version =
         Assembly.GetExecutingAssembly().GetName().Version?.ToString(3) ?? "0.0.0";
 
-    // SourceRevisionId (set by ClaudeDo.Worker.csproj's git-rev-parse build target) is appended
-    // by the SDK to InformationalVersion as "+{sha}" -- take the segment after the LAST '+' so
-    // this stays correct even when MinVer's own pre-release metadata already contains a '+'.
-    private static readonly string? BuildSha = ParseBuildSha(
-        Assembly.GetExecutingAssembly().GetCustomAttribute<AssemblyInformationalVersionAttribute>()?.InformationalVersion);
-
-    internal static string? ParseBuildSha(string? informationalVersion)
-    {
-        if (string.IsNullOrEmpty(informationalVersion)) return null;
-        var plusIndex = informationalVersion.LastIndexOf('+');
-        if (plusIndex < 0 || plusIndex == informationalVersion.Length - 1) return null;
-        return informationalVersion[(plusIndex + 1)..];
-    }
-
     private readonly QueueService _queue;
     private readonly IQueueWaker _waker;
     private readonly AgentFileService _agentService;
@@ -233,11 +219,6 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
 
     public string Ping() => $"pong v{Version}";
 
-    /// <summary>Lets the UI detect a worker that's still running an older build than the code it's
-    /// comparing against (e.g. a just-merged main) — a separate diagnostic rather than extending
-    /// Ping's "pong vX.Y.Z" text, since that format isn't ours to break for any existing caller.</summary>
-    public WorkerBuildInfoDto GetWorkerBuildInfo() => new(BuildSha);
-
     public IReadOnlyList<ActiveTaskDto> GetActive()
     {
         return _queue.GetActive()