refactor(aisidebar): restructure project and implement reasoning mode toggle

- Reorganize project structure and file locations
- Add ReasoningController to manage model selection and reasoning mode
- Update design and requirements for reasoning mode toggle
- Implement model switching between Qwen3-4B-Instruct and Qwen3-4B-Thinking models
- Remove deprecated files and consolidate project layout
- Add new steering and specification documentation
- Clean up and remove unnecessary files and directories
- Prepare for enhanced AI sidebar functionality with more flexible model handling

.kiro/steering/structure.md

@@ -0,0 +1,70 @@
+---
+inclusion: always
+---
+
+# Project Structure
+
+## File Organization
+
+```
+aisidebar/
+├── __init__.py              # Module exports (AISidebar class)
+├── aisidebar.py             # Main RevealerWindow implementation
+├── chat_widget.py           # Chat UI widget with message handling
+├── ollama_client.py         # HTTP client for Ollama REST API
+├── ollama_monitor.py        # Availability monitoring with callbacks
+├── conversation_manager.py  # Conversation persistence layer
+└── data/
+    └── conversations/       # JSON conversation files (auto-created)
+        └── default.json     # Default conversation transcript
+```
+
+## Module Responsibilities
+
+### `aisidebar.py`
+- Main window class extending `widgets.RevealerWindow`
+- Handles slide-in animation from left side
+- Manages window visibility and keyboard focus
+- Integrates with Ignis WindowManager
+
+### `chat_widget.py`
+- Complete chat UI implementation
+- Message list rendering and scrolling
+- Input handling and submission
+- Background thread management for AI requests
+- Ollama availability monitoring integration
+
+### `ollama_client.py`
+- Low-level HTTP client for Ollama API
+- Model listing with caching
+- Blocking chat API calls
+- Connection health checking
+- Graceful error handling without exceptions
+
+### `ollama_monitor.py`
+- Periodic availability checking (30s interval)
+- Callback-based state change notifications
+- GLib timeout integration for non-blocking checks
+
+### `conversation_manager.py`
+- JSON-based conversation persistence
+- Atomic file writes for data safety
+- Message validation (system/user/assistant roles)
+- Timestamp tracking for messages
+
+## Naming Conventions
+
+- Private methods/attributes: `_method_name`, `_attribute_name`
+- Widget references: `self._widget_name` (e.g., `self._entry`, `self._message_list`)
+- CSS classes: kebab-case (e.g., `ai-sidebar`, `ai-sidebar-content`)
+- Constants: UPPER_SNAKE_CASE (e.g., `VALID_ROLES`, `DEFAULT_CONVERSATION_ID`)
+
+## Code Style
+
+- Type hints on function signatures
+- Docstrings for classes and public methods
+- Dataclasses for structured data (`ConversationState`)
+- Context managers for file operations
+- Property decorators for computed attributes
+- Threading: daemon threads for background work
+- Error messages: user-friendly with actionable instructions