feat(worker): register planning services and add Merge-all hub methods

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ClaudeDo.Worker/Planning/PlanningWireDtos.cs

@@ -0,0 +1,17 @@
+namespace ClaudeDo.Worker.Planning;
+
+public sealed record SubtaskDiffDto(
+    string SubtaskId,
+    string Title,
+    string BranchName,
+    string BaseCommit,
+    string HeadCommit,
+    string? DiffStat,
+    string UnifiedDiff);
+
+public sealed record CombinedDiffResultDto(
+    bool Success,
+    string? IntegrationBranch,
+    string? UnifiedDiff,
+    string? FirstConflictSubtaskId,
+    IReadOnlyList<string>? ConflictedFiles);