chore(zsh): remove no_beep option

The terminal beep is already disabled at the system level, making this
zsh-level suppression redundant.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: nkoji21

.zshrc

@@ -130,8 +130,6 @@ man() {
 
 # ===== オプション =====
 
-# ビープ音を無効化
-setopt no_beep
 
 # ===== プラグイン =====