Add comprehensive Sphinx documentation with GitHub Pages deployment

- Complete documentation structure with index, quickstart, examples, and API reference
- Sphinx configuration with RTD theme, MyST parser, and autodoc
- GitHub Actions workflow for automated documentation building and deployment
- Local development tools (Makefile, build scripts)
- Comprehensive examples covering basic usage, security, and performance
- API documentation for core, CLI, and exceptions modules

docs/api/cli.md

@@ -0,0 +1,44 @@
+# CLI API
+
+The command-line interface module provides functions for the tzst CLI tool.
+
+```{eval-rst}
+.. automodule:: tzst.cli
+   :members:
+   :undoc-members:
+   :show-inheritance:
+```
+
+## Main Functions
+
+### main
+
+```{eval-rst}
+.. autofunction:: tzst.cli.main
+```
+
+### create_parser
+
+```{eval-rst}
+.. autofunction:: tzst.cli.create_parser
+```
+
+## Utility Functions
+
+### print_banner
+
+```{eval-rst}
+.. autofunction:: tzst.cli.print_banner
+```
+
+### format_size
+
+```{eval-rst}
+.. autofunction:: tzst.cli.format_size
+```
+
+### validate_compression_level
+
+```{eval-rst}
+.. autofunction:: tzst.cli.validate_compression_level
+```