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.

src/ClaudeDo.Worker/Lifecycle/LegacyWorktreeFolderRecovery.cs

@@ -1,6 +1,7 @@
 using ClaudeDo.Data;
 using ClaudeDo.Data.Models;
 using ClaudeDo.Data.Repositories;
+using ClaudeDo.Worker.Hub;
 using Microsoft.EntityFrameworkCore;
 
 namespace ClaudeDo.Worker.Lifecycle;
@@ -13,16 +14,21 @@ namespace ClaudeDo.Worker.Lifecycle;
 /// </summary>
 public sealed class LegacyWorktreeFolderRecovery : IHostedService
 {
+    public const string Phase = "legacy-worktrees";
+
     private const string LegacyFolderName = ".claudedo-worktrees";
 
     private readonly IDbContextFactory<ClaudeDoDbContext> _dbFactory;
+    private readonly HubBroadcaster _broadcaster;
     private readonly ILogger<LegacyWorktreeFolderRecovery> _logger;
 
     public LegacyWorktreeFolderRecovery(
         IDbContextFactory<ClaudeDoDbContext> dbFactory,
+        HubBroadcaster broadcaster,
         ILogger<LegacyWorktreeFolderRecovery> logger)
     {
         _dbFactory = dbFactory;
+        _broadcaster = broadcaster;
         _logger = logger;
     }
 
@@ -40,6 +46,8 @@ public sealed class LegacyWorktreeFolderRecovery : IHostedService
                 LegacyFolderName, affected.Count, string.Join(", ", affected));
         else
             _logger.LogInformation("Legacy worktree folder recovery: no lists affected");
+
+        await _broadcaster.OperationProgress(OperationProgressOpKeys.StartupRecovery, Phase, lists.Count, lists.Count);
     }
 
     public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;