fix: Phase completion check runs regardless of branch/merge status

handleTaskCompleted and handlePhaseAllTasksDone both bailed early when
initiative had no branch, silently skipping phase status transitions.
Also, merge failures would skip the phase completion check entirely.

- Decouple phase completion check from branch existence
- Wrap merge in try/catch so phase check runs even if merge fails
- Route updateTaskStatus through dispatchManager.completeTask when
  completing, so the task:completed event fires for orchestration

apps/server/trpc/routers/task.ts

@@ -50,6 +50,14 @@ export function taskProcedures(publicProcedure: ProcedureBuilder) {
             message: `Task '${input.id}' not found`,
           });
         }
+
+        // Route through dispatchManager when completing — emits task:completed
+        // event so the orchestrator can check phase completion and merge branches
+        if (input.status === 'completed' && ctx.dispatchManager) {
+          await ctx.dispatchManager.completeTask(input.id);
+          return (await taskRepository.findById(input.id))!;
+        }
+
         return taskRepository.update(input.id, { status: input.status });
       }),