🔄 Refresh Access Token

Endpoint: POST /api/solver/auth/refresh
Auth Required: ❌ No (Refresh Token Required)
Content-Type: application/json

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📌 Description

This endpoint allows a solver to generate a new access token using a valid refresh token.

Access tokens are short-lived for security reasons.
When an access token expires, the frontend should use this endpoint to obtain a new one without forcing the solver to log in again.

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🔐 Authentication

This endpoint does not require an access token.

Instead, a valid refresh token must be provided in the request body.

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🧾 Request Body

```json { "refresh_token": "eyJhbGciOiJIUzI1NiIsInR5cCI6..." }