docs/refactor: improve read API, fix setup.py, add type hints and comprehensive docs

[jimmyliuzg]

Summary

Improves the read-only CellarTracker API with better documentation, type safety, and bug fixes. No breaking changes — all existing interfaces are preserved.

Changes

Bug Fix

• setup.py: Removed trailing comma after list ( -> ). The comma was creating a tuple instead of a list, which could cause pip to silently fail to install the dependency.

Documentation

• README.md (new): Full reference with quick start, method table with descriptions, common field reference, CLI usage examples, and authentication notes
• Docstrings: Every public method on now has detailed docstrings documenting return values and key fields

Type Safety

• Fixed type annotations: → in both and
• Added return type hints: on all data methods

CLI Improvements

• Added flag: parses the API response back to structured JSON for easier consumption
• Added flag: shows available tables with descriptions
• Added examples section to argument parser help
• Added human-readable table descriptions in help output

Compatibility

• All existing method signatures unchanged (same return types, same parameters)
• Uses existing imports for broader Python version compatibility