Add optional OpenTelemetry Netty server instrumentation

- Update lys.version to 2026.04.14

- Add optional compileOnly dependency on opentelemetry-netty-4.1 in rbcs-server

- Add runtime guard to only activate instrumentation when OTel classes are on classpath

- Insert OTel combined handler after HttpServerCodec in the Netty pipeline

- Add requires-static JPMS directives for optional module support

rbcs-server/src/main/resources/net/woggioni/rbcs/server/rbcs-default.xml

@@ -2,7 +2,8 @@
 <rbcs:server
              xmlns:xs="http://www.w3.org/2001/XMLSchema-instance"
              xmlns:rbcs="urn:net.woggioni.rbcs.server"
-             xs:schemaLocation="urn:net.woggioni.rbcs.server jpms://net.woggioni.rbcs.server/net/woggioni/rbcs/server/schema/rbcs-server.xsd">
+             xs:schemaLocation="urn:net.woggioni.rbcs.server jpms://net.woggioni.rbcs.server/net/woggioni/rbcs/server/schema/rbcs-server.xsd"
+             enable-telemetry="false">
     <bind host="127.0.0.1" port="8080" incoming-connections-backlog-size="1024"/>
     <cache xs:type="rbcs:fileSystemCacheType" path="${sys:java.io.tmpdir}/rbcs" max-age="P7D"/>
 </rbcs:server>

rbcs-server/src/main/resources/net/woggioni/rbcs/server/schema/rbcs-server.xsd

@@ -59,6 +59,14 @@
                 </xs:documentation>
             </xs:annotation>
         </xs:attribute>
+        <xs:attribute name="enable-telemetry" type="xs:boolean" use="optional" default="false">
+            <xs:annotation>
+                <xs:documentation>
+                    Enable OpenTelemetry distributed tracing for the server.
+                    Even when enabled, telemetry only activates if OpenTelemetry classes are present on the classpath.
+                </xs:documentation>
+            </xs:annotation>
+        </xs:attribute>
     </xs:complexType>
 
     <xs:complexType name="bindType">