fix: Resolve javadoc errors for Maven publish

- Fix heading hierarchy in CallSession (h3 -> h2)
- Escape HTML characters in ResponseState comment
- Correct @param tags in ResponseEncoder.writeError()

These fixes allow successful javadoc generation and Maven artifact publishing.

src/main/java/com/reliancy/jabba/CallSession.java

@@ -17,7 +17,7 @@ import java.util.concurrent.Executor;
  * For example request and response objects are accessible.
  * The session is updated at process phase of each processor.
  * 
- * <h3>Instance Counting and Multi-Threading</h3>
+ * <h2>Instance Counting and Multi-Threading</h2>
  * CallSession tracks how many threads are currently using it via an atomic counter.
  * This enables safe async processing where a single session is shared across multiple threads:
  * 

src/main/java/com/reliancy/jabba/ResponseEncoder.java

@@ -196,11 +196,9 @@ public class ResponseEncoder implements Appendable,Closeable{
      * for json,xml and plain we render into a message template for the rest we do nothing.
      * this method returns true if a response was generated. in overloaded methods
      * if false is returned we can generate response the status is set to 500 already.
-     * @param req incoming request
      * @param ex exception state
-     * @param resp response to generate
-     * @return true if handled else it signifies we should do somthing in overloads.
-     * @throws IOException
+     * @return this encoder for chaining
+     * @throws IOException if writing the error response fails
      */
     public ResponseEncoder writeError(Throwable ex) throws IOException{
         log().error("error:",ex);

src/main/java/com/reliancy/jabba/ResponseState.java

@@ -9,7 +9,7 @@ package com.reliancy.jabba;
 
 /**
  * Represents the lifecycle state of a Response object.
- * Response goes through stages: created -> configuring -> committed -> writing <-> written -> completed
+ * Response goes through stages: created -&gt; configuring -&gt; committed -&gt; writing &lt;-&gt; written -&gt; completed
  */
 public enum ResponseState {
     /** Response object created, nothing configured yet */