Check HTTP status codes in isTerminalError

Enhance isTerminalError() to check HTTP status codes before falling back
to error message string matching. This provides more reliable error
classification.

Priority order:
1. HTTP status code (if available) - 4xx except 429 are terminal
2. Error message patterns (fallback)

This ensures:
- 400, 401, 403, 404 -> terminal (don't retry)
- 429, 503, 5xx -> retryable (will retry)
- Non-HTTP errors -> check message strings

Addresses review feedback on PR #320

Author: samikshya-db

telemetry/errors.go

@@ -13,7 +13,12 @@ func isTerminalError(err error) bool {
 		return false
 	}
 
-	// Check error message patterns for terminal errors
+	// Priority 1: Check HTTP status code if available (most reliable)
+	if httpErr, ok := extractHTTPError(err); ok {
+		return isTerminalHTTPStatus(httpErr.statusCode)
+	}
+
+	// Priority 2: Fall back to error message patterns
 	errMsg := strings.ToLower(err.Error())
 	terminalPatterns := []string{
 		"authentication failed",