chore: remove unused WarningType enum and create factory from ProcessingWarning

src/main/java/com/williamcallahan/javachat/domain/markdown/ProcessingWarning.java

@@ -4,63 +4,14 @@
  * Represents a non-fatal warning encountered during markdown processing.
  * Used for structured error reporting instead of silent failures.
  */
-public record ProcessingWarning(String message, WarningType type, int position, String context) {
+public record ProcessingWarning(String message, int position, String context) {
 
     public ProcessingWarning {
         if (message == null || message.trim().isEmpty()) {
             throw new IllegalArgumentException("Warning message cannot be null or empty");
         }
-        if (type == null) {
-            throw new IllegalArgumentException("Warning type cannot be null");
-        }
         if (position < 0) {
             throw new IllegalArgumentException("Warning position must be non-negative");
         }
     }
-
-    /**
-     * Creates a processing warning with minimal context.
-     * @param message the warning message
-     * @param type the warning type
-     * @param position position in document
-     * @return new ProcessingWarning instance
-     */
-    public static ProcessingWarning create(String message, WarningType type, int position) {
-        return new ProcessingWarning(message, type, position, "");
-    }
-
-    /**
-     * Warning types for categorization.
-     */
-    public enum WarningType {
-        /**
-         * Malformed enrichment marker.
-         */
-        MALFORMED_ENRICHMENT,
-
-        /**
-         * Invalid citation format.
-         */
-        INVALID_CITATION,
-
-        /**
-         * Unclosed code block.
-         */
-        UNCLOSED_CODE_BLOCK,
-
-        /**
-         * Nested structure issue.
-         */
-        NESTED_STRUCTURE,
-
-        /**
-         * Unknown enrichment type.
-         */
-        UNKNOWN_ENRICHMENT_TYPE,
-
-        /**
-         * General parsing issue.
-         */
-        PARSING_ISSUE
-    }
 }