Implement complete nested todo tree web app MVP

This commit implements a fully functional self-hosted task decomposition engine with:

Backend (FastAPI + SQLite):
- RESTful API with full CRUD operations for projects and tasks
- Arbitrary-depth hierarchical task structure using self-referencing parent_task_id
- JSON import endpoint for seeding projects from LLM-generated breakdowns
- SQLAlchemy models with proper relationships and cascade deletes
- Status tracking (backlog, in_progress, blocked, done)
- Auto-generated OpenAPI documentation

Frontend (React + Vite + Tailwind):
- Dark cyberpunk theme with orange accents
- Project list page with create/import/delete functionality
- Dual view modes:
  * Tree View: Collapsible hierarchical display with inline editing
  * Kanban Board: Drag-and-drop status management
- Real-time CRUD operations for tasks and subtasks
- JSON import modal with validation
- Responsive design optimized for desktop

Infrastructure:
- Docker setup with multi-stage builds
- docker-compose for orchestration
- Nginx reverse proxy for production frontend
- Named volume for SQLite persistence
- CORS configuration for local development

Documentation:
- Comprehensive README with setup instructions
- Example JSON import file demonstrating nested structure
- API endpoint documentation
- Data model diagrams

.gitignore

@@ -0,0 +1,43 @@
+# Python
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+.Python
+venv/
+env/
+ENV/
+*.egg-info/
+.pytest_cache/
+
+# Database
+*.db
+*.sqlite
+*.sqlite3
+
+# Node
+node_modules/
+dist/
+build/
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Environment
+.env
+.env.local
+.env.*.local
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Docker
+docker-compose.override.yml