In my opinion, deprecateAliases should also check hiddenAliases

When deprecating a command alias, the natural combination is:

1. Hide it from help text (so new users don't discover it)
2. Warn existing users that it's deprecated (so they migrate)

Currently, deprecateAliases only checks aliases:

// command.js – warnIfCommandDeprecated()
if (this.ctor.deprecateAliases && this.ctor.aliases.includes(id)) {

This means there's no way to get both behaviors. You either:

• Put the alias in aliases + deprecateAliases: true → warns, but still shows in help
• Put the alias in hiddenAliases + deprecateAliases: true → hidden, but no warning
• Put it in both aliases and hiddenAliases → aliases wins, still shows in help

Proposed fix: warnIfCommandDeprecated should check both arrays.

This would let you do the standard deprecation flow: move an alias from aliases to hiddenAliases, set deprecateAliases: true, and get the expected behavior - hidden from help, warns on use.