IRC: add the firmware version to the CTCP VERSION reply

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0162FokPdvY2KsS4NBfwyWPk

test/test_irc_session/test_irc_session.cpp

@@ -5,6 +5,7 @@
 
 #include "../memory_store.h"
 #include "irc_session.h"
+#include "version.h"
 
 using namespace roro;
 
@@ -326,7 +327,7 @@ void test_action_and_ctcp_version() {
     f.take();
     f.recv(":alice!u@h PRIVMSG roro :\x01VERSION\x01");
     f.take();
-    TEST_ASSERT_TRUE(f.sent("NOTICE alice :\x01VERSION roro9stack\x01"));
+    TEST_ASSERT_TRUE(f.sent(std::string("NOTICE alice :\x01VERSION roro9stack ") + versionString() + "\x01"));
 }
 
 void test_topic_is_kept() {