fix(api): propagate database errors correctly with 500 status code

[panditshubham766-dotcom]

Summary

Fixed a critical backend issue where several API routes were catching database/query failures but hiding them by returning a 200 OK status with empty fallback data. Unhandled exceptions now correctly propagate as a 500 Internal Server Error to prevent the frontend from misinterpreting database failures as successful empty responses.

Closes #1792

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Type of Change

• Bug fix

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Changes Made

• Audited caught exceptions across 11 affected API routes (including local-coding, notifications, user accounts, and wakatime endpoints).
• Replaced silent 200 error-masking blocks with proper NextResponse.json error payloads containing a 500 status code.
• Carefully preserved legitimate 200 empty states (like empty pins data or unconfigured profiles) so normal application behavior remains uninterrupted.

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How to Test

1. Break the local database connection configuration intentionally.
2. Hit the updated endpoints (e.g., /api/local-coding/stats).
3. Verify via the network tab that the API rejects the request with a clean 500 Internal Server Error payload instead of a fake 200 OK.

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