fix: suppress p10k instant prompt warning

[atomantic]

Summary

• Adds typeset -g POWERLEVEL9K_INSTANT_PROMPT=quiet before the instant prompt block in .zshrc
• Suppresses the console output warning during zsh initialization while keeping instant prompt enabled

Test plan

• Open a new terminal and verify no P10k instant prompt warning appears
• Verify zsh still starts quickly with instant prompt active

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Suppresses the Powerlevel10k instant prompt warning during zsh startup by configuring instant prompt to run in “quiet” mode, while keeping instant prompt enabled near the top of .zshrc.

Changes:

• Sets POWERLEVEL9K_INSTANT_PROMPT=quiet before the p10k instant prompt sourcing block.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

You can also share your feedback on Copilot code review. Take the survey.