🔒 [security fix] Prevent sensitive data exposure in debug logs

[gasatrya]

🎯 What: The vulnerability fixed is the exposure of sensitive git diff data in the extension's debug logs.
⚠️ Risk: If debug logging is enabled, the full git diff (which may contain proprietary code, API keys, or other secrets) is written to the VS Code Output Channel. This data could be leaked if a user shares their logs for troubleshooting or if an unauthorized party gains access to the environment.
🛡️ Solution: Modified the logDebug call in src/commands.ts to log the character count of the prompts instead of the raw strings. This provides sufficient information for debugging prompt generation while maintaining data privacy.

---

PR created automatically by Jules for task 17789887192403163066 started by @gasatrya

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.