fix(desktop): add sessions_spawn to tool groups

The sessions_spawn tool was not showing in the desktop tools UI because
TOOL_GROUPS and ALL_KNOWN_TOOLS were missing the subagent group.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/desktop/electron/ipc/agent.ts

@@ -13,6 +13,7 @@ const TOOL_GROUPS: Record<string, string[]> = {
   'group:runtime': ['exec', 'process'],
   'group:web': ['web_search', 'web_fetch'],
   'group:memory': ['memory_get', 'memory_set', 'memory_delete', 'memory_list'],
+  'group:subagent': ['sessions_spawn'],
 }
 
 // All known tool names (for display when agent not available)
@@ -21,6 +22,7 @@ const ALL_KNOWN_TOOLS = [
   ...TOOL_GROUPS['group:runtime'],
   ...TOOL_GROUPS['group:web'],
   ...TOOL_GROUPS['group:memory'],
+  ...TOOL_GROUPS['group:subagent'],
 ]
 
 /**