fix: enforce exact question count per category (CT-74)

[ThanasisSoftwareDeveloper]

Summary

Describe what this PR changes and why.

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Type of Change

• Feature
• Bug fix
• Refactor
• Documentation
• Test
• Chore

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Changes

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Testing

• npm run lint
• npm test
• npm run build
• Manual browser check, if UI or workflow changed

If any check was skipped, explain why:

N/A

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Screenshots or Recording

Add screenshots or a short recording for UI changes.

N/A

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DashFetch Workflow Impact

Check any flow touched by this PR:

• Job description paste/upload
• File parsing
• Job summary extraction
• Interview question generation
• Mock interview practice
• Session storage/navigation
• API routes
• Supabase schema or data access
• Groq prompt or AI response normalization
• No user-facing workflow changed

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Deployment Notes

• No deployment notes
• Environment variables changed
• Supabase schema changed
• Next.js config or route behavior changed
• Dependencies changed

Details:

N/A

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Linked Issues

Closes #

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Reviewer Notes

Mention tradeoffs, follow-up work, or areas where you want focused review.

N/A

[RBanner]

Reviewed and Approved.