Add rspamd as a second spam filter alongside SpamAssassin

Closes: #36

pkg/analyzer/parser.go

@@ -256,6 +256,33 @@ func (e *EmailMessage) GetSpamAssassinHeaders() map[string]string {
 	}
 
 	for _, headerName := range saHeaders {
+		if values, ok := e.Header[headerName]; ok && len(values) > 0 {
+			for _, value := range values {
+				if strings.TrimSpace(value) != "" {
+					headers[headerName] = value
+					break
+				}
+			}
+		} else if value := e.Header.Get(headerName); value != "" {
+			headers[headerName] = value
+		}
+	}
+
+	return headers
+}
+
+// GetRspamdHeaders extracts rspamd-related headers
+func (e *EmailMessage) GetRspamdHeaders() map[string]string {
+	headers := make(map[string]string)
+
+	rspamdHeaders := []string{
+		"X-Spamd-Result",
+		"X-Rspamd-Score",
+		"X-Rspamd-Action",
+		"X-Rspamd-Server",
+	}
+
+	for _, headerName := range rspamdHeaders {
 		if value := e.Header.Get(headerName); value != "" {
 			headers[headerName] = value
 		}