prompt-tutor example: interval = 1 keeps the pending Review timer counting

[shayan-ys]

📝 Summary

This PR adds interval = 1 to the prompt-tutor integration example. With only watch, devdash reruns prompt-tutor --once when its data files change, so a pending Review's reviewing… Ns timer and spinner stayed frozen.

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🛠️ Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• ⚡ Performance / Refactor (code optimization without behavior changes)
• 📚 Documentation update

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🔍 Changes Made

• README.md: the prompt-tutor example config adds interval = 1, and step 4 explains why.
• config.example.toml: the commented prompt-tutor example adds # interval = 1, and its comment now explains the interval instead of saying to omit it.

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🧪 How to Test

1. Add interval = 1 to the prompt-tutor integration in your devdash config.
2. Run devdash.
3. Verify that the PROMPT TUTOR header shows fetched 0s ago · next fetch 1s and that a pending Review's timer counts up.

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✅ Review and verification

• Review path: low risk self-review; omitted optional reviews: none.
• Verification: ran devdash with interval = 1 in a pty; the PROMPT TUTOR header showed fetched 0s ago · next fetch 1s. prompt-tutor --once takes about 40 ms per run.
• Declined findings: none.
• Remaining non-blocking findings: none.