refactor(gui): reorganize background rendering and layout helpers

- Moved background rendering functionality from the editor to a dedicated GUI module, enhancing modularity and separation of concerns.
- Introduced layout helpers for consistent theme-aware sizing across the GUI, improving UI consistency and maintainability.
- Updated CMake configuration to reflect the new structure, ensuring proper linkage of the background renderer and layout helpers.

Benefits:
- Improved organization of GUI components, facilitating easier updates and enhancements.
- Enhanced user interface consistency through theme-aware layout management.

src/cli/agent.cmake

@@ -1,12 +1,18 @@
 set(YAZE_AGENT_SOURCES
+  # Core infrastructure
+  cli/service/command_registry.cc
   cli/service/agent/proposal_executor.cc
   cli/handlers/agent/todo_commands.cc
   cli/service/agent/conversational_agent_service.cc
   cli/service/agent/simple_chat_session.cc
   cli/service/agent/enhanced_tui.cc
   cli/service/agent/tool_dispatcher.cc
+  
+  # Advanced features
   cli/service/agent/learned_knowledge_service.cc
   cli/service/agent/todo_manager.cc
+  cli/service/agent/advanced_routing.cc
+  cli/service/agent/agent_pretraining.cc
   cli/service/agent/vim_mode.cc
   cli/service/ai/ai_service.cc
   cli/service/ai/ai_action_parser.cc