feat(sse): add raw frame contracts

Author: loong10k

src/main/java/io/github/easy4j/hermes/api/sse/SseConsumerException.java

@@ -0,0 +1,17 @@
+package io.github.easy4j.hermes.api.sse;
+
+/** Signals a business SSE consumer failure without misclassifying it as JSON decoding. */
+public final class SseConsumerException extends RuntimeException {
+    private final String eventId;
+    private final String eventName;
+
+    public SseConsumerException(SseFrame frame, Throwable cause) {
+        super("Hermes SSE consumer failed for event "
+                + (frame.getEvent() == null ? "<unnamed>" : frame.getEvent()), cause);
+        this.eventId = frame.getId();
+        this.eventName = frame.getEvent();
+    }
+
+    public String getEventId() { return eventId; }
+    public String getEventName() { return eventName; }
+}