feat: dockerize app and convert to pyproject setup

- Add pyproject.toml with proper metadata and dependency groups
- Create multi-stage Dockerfile for backend
- Add docker-compose.yml with dev/prod profiles
- Create frontend Dockerfile with nginx
- Add .dockerignore for optimized builds
- Update README with Docker instructions and troubleshooting
- Remove requirements.txt in favor of pyproject.toml
- Ensure data persistence with Docker volumes

openspec/changes/dockerize-and-pyproject-setup/specs/python-packaging/spec.md

@@ -0,0 +1,32 @@
+## ADDED Requirements
+
+### Requirement: pyproject.toml replaces requirements.txt
+The project SHALL use `pyproject.toml` as the primary dependency and build configuration file.
+
+#### Scenario: Install from pyproject.toml
+- **WHEN** developer runs `pip install -e .`
+- **THEN** all runtime dependencies are installed correctly
+- **AND** the package is installed in editable mode
+
+### Requirement: Dependencies are properly declared
+The `pyproject.toml` SHALL declare all runtime, development, and optional dependencies in appropriate groups.
+
+#### Scenario: Install with dev dependencies
+- **WHEN** developer runs `pip install -e ".[dev]"`
+- **THEN** testing tools (pytest, pytest-asyncio) are installed
+- **AND** development tools are available
+
+### Requirement: Package metadata is complete
+The `pyproject.toml` SHALL include project metadata such as name, version, description, authors, and license.
+
+#### Scenario: Package info is accessible
+- **WHEN** user queries package metadata via `pip show backup-tool`
+- **THEN** name, version, description, and author information are displayed
+
+### Requirement: Console scripts are defined
+The `pyproject.toml` SHALL define console entry points for running the application.
+
+#### Scenario: Run via CLI command
+- **WHEN** user runs `backup-tool` or `uvicorn backup_tool.main:app`
+- **THEN** the application starts successfully
+- **AND** the console script is properly registered