Refactor CLI and consolidate ZON conversion functionality

- Move `zon2json` command from `main.py` to `__main__.py`
- Create shared `convert_zon_to_json` function for consistent JSON conversion
- Update pyproject.toml to point `zon2json` script to new location
- Update README with `uv run` prefix for CLI commands
- Expose key functions in `__init__.py` for easier importing
- Remove redundant `main.py` file

README.md

@@ -62,7 +62,7 @@ The package provides a command-line interface with the following commands:
 Download and extract dependencies from a ZON file:
 
 ```bash
-zig-fetch download examples/test.zon
+uv run zig-fetch download examples/test.zon
 ```
 
 This will download all dependencies specified in the ZON file to `~/.cache/zig/p` and extract them to directories named after their hash values.
@@ -72,13 +72,7 @@ This will download all dependencies specified in the ZON file to `~/.cache/zig/p
 Convert a ZON file to JSON:
 
 ```bash
-zig-fetch convert examples/test.zon
-```
-
-Or use the dedicated command:
-
-```bash
-zon2json examples/test.zon
+uv run zig-fetch convert examples/test.zon
 ```
 
 Options: