Phase 5 scalability and polish:
- Add tags + prompt_tags junction tables replacing JSON column
- Migrate existing JSON tags via json_each() on startup
- Rewrite all tag queries to use junction tables (O(1) vs O(n))
- Simplify rename/delete/merge tag operations to single SQL
- Batch-attach preview images to prompt list responses (fix N+1)
- Fix fetchone() fragility under thread contention (defensive defaults)
- Add Google-style docstrings to main node files (prompt_manager.py, prompt_manager_text.py)
- Enhance database module docstrings with detailed parameter and return documentation
- Add comprehensive docstrings to all utils modules with usage examples
- Document API endpoints and configuration classes thoroughly
- Update module-level docstrings in all __init__.py files
- Ensure consistent naming (ComfyUI_PromptManager) across all documentation
- Follow Python best practices for docstring formatting