Refactor CLI commands into separate classes

[pixelate]

Summary

• Each command (`sync`, `analyze`, `set`, `help`) is now its own class under `lib/wavesync/commands/`
• `Command` base class provides a `parse_options` helper that wires in `--config`, yields for command-specific options, and returns parsed options + loaded config
• Command metadata (`name`, `description`, `options`, `subcommands`) is declared as class-level attributes on each command
• `Help` generates its output from command metadata rather than hardcoded strings
• `CLI` is now a thin dispatcher