fix: Handle wrapped OpenAI authentication errors in API key validation

The embedding service wraps OpenAI AuthenticationError as EmbeddingAPIError,
causing API key validation to fail silently instead of blocking operations.

- Add specific handling for EmbeddingAPIError with 401 status codes
- Detect authentication errors by checking for '401' and 'incorrect/invalid' keywords
- Ensure API key validation properly blocks crawl operations
- Add detailed logging to identify wrapped error types

This fixes the issue where invalid API keys would start crawls that fail
silently instead of showing immediate error messages in the UI.

python/src/server/api_routes/knowledge_api.py

@@ -104,6 +104,7 @@ async def _validate_openai_api_key() -> None:
     from ..services.embeddings.embedding_exceptions import (
         EmbeddingAuthenticationError,
         EmbeddingQuotaExhaustedError,
+        EmbeddingAPIError,
     )
     
     try:
@@ -149,10 +150,63 @@ async def _validate_openai_api_key() -> None:
                 "tokens_used": getattr(e, "tokens_used", None),
             }
         ) from None
+    except EmbeddingAPIError as e:
+        error_str = str(e)
+        logger.error(f"❌ OpenAI API error during validation: {error_str}")
+        
+        # Check if this is an authentication error (401 status code)
+        if ("401" in error_str and ("invalid" in error_str.lower() or "incorrect" in error_str.lower())):
+            logger.error("🔍 Detected OpenAI authentication error in EmbeddingAPIError")
+            raise HTTPException(
+                status_code=401,
+                detail={
+                    "error": "Invalid OpenAI API key",
+                    "message": "Please verify your OpenAI API key in Settings before starting a crawl.",
+                    "error_type": "authentication_failed"
+                }
+            ) from None
+        else:
+            # Other API errors should also block the operation
+            logger.error("🔍 Other OpenAI API error during validation")
+            raise HTTPException(
+                status_code=502,
+                detail={
+                    "error": "OpenAI API error",
+                    "message": "OpenAI API error during validation. Please check your API key configuration.",
+                    "error_type": "api_error"
+                }
+            ) from None
     except Exception as e:
+        error_str = str(e)
+        logger.error(f"❌ API key validation failed: {error_str}")
+        
+        # Check if this is an authentication error wrapped as a generic exception
+        if ("401" in error_str and ("invalid" in error_str.lower() or "incorrect" in error_str.lower() or "authentication" in error_str.lower())):
+            logger.error("🔍 Detected wrapped OpenAI authentication error")
+            raise HTTPException(
+                status_code=401,
+                detail={
+                    "error": "Invalid OpenAI API key",
+                    "message": "Please verify your OpenAI API key in Settings before starting a crawl.",
+                    "error_type": "authentication_failed"
+                }
+            ) from None
+        
+        # Check if this is a quota error wrapped as a generic exception  
+        if ("quota" in error_str.lower() or "billing" in error_str.lower() or "credits" in error_str.lower()):
+            logger.error("🔍 Detected wrapped OpenAI quota error")
+            raise HTTPException(
+                status_code=429,
+                detail={
+                    "error": "OpenAI quota exhausted",
+                    "message": "Your OpenAI API key has no remaining credits. Please add credits to your account.",
+                    "error_type": "quota_exhausted"
+                }
+            ) from None
+        
         # For any other errors, log them but allow the operation to continue
         # The error will be caught later during actual processing
-        logger.warning(f"⚠️ API key validation failed with unexpected error: {e}")
+        logger.warning(f"⚠️ API key validation failed with unexpected error (allowing operation to continue): {e}")
         # Don't block the operation for unexpected validation errors
         pass