Feature Request: Add man page support to help AI tools and users discover commands/key bindings

Is your feature request related to a problem? Please describe.

When using AI agents or automation tools to discover how to use spotify_player, the tools often try to look up the manual page by running man spotify_player, which fails:

$ man spotify_player
No manual entry for spotify_player

Command exited with code 16.

While spotify_player -h works, having a proper manual page makes the tool much more compliant with standard Linux/Unix CLI ecosystems. It gives both users and AI agents a standard way to read detailed documentation offline, including the default key bindings and advanced configuration options, which currently require digging through GitHub's markdown files.

Describe the solution you'd like

Generate and include a man page during the build/installation process for Linux/Unix systems.

Ideally, the manual page would include:

1. Standard CLI arguments (same as -h).
2. Detailed breakdown of available subcommands (e.g. get, playback).
3. A complete list of default key bindings (very helpful to have available offline without launching the TUI).
4. Locations for configuration files (~/.config/spotify-player/).

Describe alternatives you've considered

Currently, the alternative is either relying purely on --help outputs (which omit the TUI keybindings and config file details) or reading the markdown docs on GitHub.

Additional context

Providing a man page could easily be achieved by using existing Rust documentation generator crates like clap_mangen to automatically generate the man page from the clap CLI definition, and then optionally appending a static section for the TUI key bindings.