Hide subagent stream events in the CLI parser

When a panel member spawned a subagent via the Agent tool, the Claude CLI
emitted the subagent's internal steps as separate top-level messages
carrying parent_tool_use_id: tool_use blocks arrived as type:"assistant"
(no handler → dropped) and the matching tool_result as type:"user", which
created a nameless, label-less collapsible box in the frontend — both in
the live stream and in the persisted history (same segment source).

Skip any top-level event with a non-empty parent_tool_use_id at the single
stream JSON parser, so subagent internals never become CliStreamEvents.
This covers worker and panel-member paths at once. The Agent tool call
itself (parent_tool_use_id=null) stays visible, and the final result event
— which aggregates subagent tokens — carries no parent_tool_use_id, so the
token balance is unaffected.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Services/ClaudeCliService.cs

@@ -385,6 +385,21 @@ public class ClaudeCliService
                     var json = JsonSerializer.Deserialize<JsonElement>(line);
                     var type = json.TryGetProperty("type", out var t) ? t.GetString() : null;
 
+                    // Subagent-Events ausblenden: Top-Level-Messages mit gesetztem
+                    // parent_tool_use_id stammen aus einem per 'Agent'-Tool gespawnten
+                    // Subagenten. Deren Interna (tool_use kommt als type:"assistant" ohne
+                    // Handler → verworfen; tool_result als type:"user" → erzeugte sonst eine
+                    // namenlose, label-lose Box) werden konsequent unterdrückt – konsistent
+                    // zum Session-Agent. Die Tool-Box des Agent-Aufrufs selbst hat
+                    // parent_tool_use_id=null und bleibt sichtbar; der finale 'result'-Event
+                    // (Tokens, inkl. aggregierter Subagent-Tokens) trägt ebenfalls keins.
+                    if (json.TryGetProperty("parent_tool_use_id", out var parentToolUseId)
+                        && parentToolUseId.ValueKind == JsonValueKind.String
+                        && !string.IsNullOrEmpty(parentToolUseId.GetString()))
+                    {
+                        continue;
+                    }
+
                     if (type == "stream_event" && json.TryGetProperty("event", out var evt))
                     {
                         var evtType = evt.TryGetProperty("type", out var et) ? et.GetString() : null;