feat(worker): surface startup recovery via OperationProgress channel

The six Lifecycle/*Recovery hosted services now broadcast one
OperationProgress("startup-recovery", <phase>, current, total) message each
after they finish, instead of leaving the UI on a bare "connecting" text
during worker startup. IslandsShellViewModel subscribes and swaps in
"Recovering... (i/n)" (existing ops.worker.startupRecovery key, no locale
changes) while Worker.IsReconnecting is true, and clears it once actually
connected so a later transient reconnect doesn't replay stale text.

OperationProgress broadcasts to Clients.All with no replay-on-connect, so a
UI that hasn't finished its SignalR handshake yet can miss some or all of
these messages and simply keep showing "connecting" as before -- accepted
rather than adding a cached-state + reconnect-replay path (mirroring
RefreshExternalMergeConflictsAsync) for what is a fast, best-effort,
local-only startup sweep with no UI-visible failure mode beyond that.

tests/ClaudeDo.Worker.Tests/Lifecycle/LegacyWorktreeFolderRecoveryTests.cs

@@ -1,4 +1,5 @@
 using ClaudeDo.Data.Models;
+using ClaudeDo.Worker.Hub;
 using ClaudeDo.Worker.Lifecycle;
 using ClaudeDo.Worker.Tests.Infrastructure;
 using Microsoft.Extensions.Logging.Abstractions;
@@ -63,9 +64,14 @@ public sealed class LegacyWorktreeFolderRecoveryTests : IDisposable
     [Fact]
     public async Task StartAsync_NoLists_DoesNotThrow()
     {
-        var sut = new LegacyWorktreeFolderRecovery(_db.CreateFactory(), NullLogger<LegacyWorktreeFolderRecovery>.Instance);
+        var hubContext = new CapturingHubContext();
+        var sut = new LegacyWorktreeFolderRecovery(
+            _db.CreateFactory(), new HubBroadcaster(hubContext), NullLogger<LegacyWorktreeFolderRecovery>.Instance);
 
         await sut.StartAsync(CancellationToken.None);
         await sut.StopAsync(CancellationToken.None);
+
+        Assert.Contains(hubContext.Proxy.Calls, c =>
+            c.Method == "OperationProgress" && (string)c.Args[0]! == "startup-recovery");
     }
 }