v0.1.2

feat: enhance task management and implementation workflow

- Introduced task progress tracking in SpecCodeLensProvider to indicate ongoing tasks.
- Updated chat participant registration to handle task start and completion events.
- Added functionality to mark tasks and subtasks as completed, preserving existing states.
- Enhanced task parsing to support heading-style tasks and their subtasks.
- Implemented a rich prompt builder for task implementation, including linked requirements and design excerpts.
- Refactored spec generation to maintain completed task states during regeneration.
- Improved error handling and user feedback in the chat interface for task-related commands.