docs: fix Homebrew tap install command

[dajiaohuang]

Closes #62

Summary

• replace the nonexistent agentiloop-agent cask token with agentiloop/tap/agent in the English README
• apply the same correction to all seven translated README files

The official tap currently defines Casks/agent.rb, so the tap-qualified command is the documented install path.

Validation

• git diff --check
• verified all eight README files contain the corrected command
• verified the live tap entry at https://github.com/AgentiLoop/homebrew-tap/blob/main/Casks/agent.rb

[github-actions]

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[AgentiLoop]

The official cask is 'agentiloop-agent' through homebrew. The AgentiLoop GitHub version is not the official one. That's our repo. The two are entirely separate.

See below, the official cask installs correctly:

[AgentiLoop]

See also: https://formulae.brew.sh/cask/agentiloop-agent