feat(auth): Implement create_refresh_token and add tests

backend/src/ea_chatbot/api/utils.py

@@ -61,6 +61,34 @@ def create_access_token(data: dict, expires_delta: Optional[timedelta] = None) -
     encoded_jwt = jwt.encode(to_encode, settings.secret_key, algorithm=settings.algorithm)
     return encoded_jwt
 
+def create_refresh_token(data: dict, expires_delta: Optional[timedelta] = None) -> str:
+    """
+    Create a JWT refresh token.
+    
+    Args:
+        data: The payload data to encode.
+        expires_delta: Optional expiration time delta.
+        
+    Returns:
+        str: The encoded JWT token.
+    """
+    to_encode = data.copy()
+    now = datetime.now(timezone.utc)
+    
+    if expires_delta:
+        expire = now + expires_delta
+    else:
+        expire = now + timedelta(days=settings.refresh_token_expire_days)
+    
+    to_encode.update({
+        "exp": expire,
+        "iat": now,
+        "iss": "ea-chatbot-api",
+        "type": "refresh"
+    })
+    encoded_jwt = jwt.encode(to_encode, settings.secret_key, algorithm=settings.algorithm)
+    return encoded_jwt
+
 def decode_access_token(token: str) -> Optional[dict]:
     """
     Decode a JWT access token.