refactor(Ex22): apply template method to Timer

Rename the virtual tick() override in PelicanTimer to doExpired()
and give the base Timer class a non-virtual tick() that checks for
expiration and dispatches to doExpired(). The exercise starting
point now matches SolutionEx22.

Co-authored-by: Qwen 3.8 27B <qwen3.8_27b-q3_k_xl@lmstudio.local>

cmat/Ex22/Timer.cpp

@@ -1,17 +1,23 @@
-
-
-#include "Timer.h"
-#include "TimerSet.h"
-
-void Timer::timeoutRequest(int seconds) { timeToGo = seconds; }
-
-Timer::Timer() : timeToGo(-1) { TimerSet::Instance().addATimer(this); }
-
-bool Timer::isExpired() {
-    if (timeToGo > 0) {
-        if (--timeToGo == 0) {
-            return true;
-        }
-    }
-    return false;
-}
+
+
+#include "Timer.h"
+#include "TimerSet.h"
+
+void Timer::timeoutRequest(int seconds) { timeToGo = seconds; }
+
+Timer::Timer() : timeToGo(-1) { TimerSet::Instance().addATimer(this); }
+
+void Timer::tick() {
+    if (isExpired()) {
+        doExpired();
+    }
+}
+
+bool Timer::isExpired() {
+    if (timeToGo > 0) {
+        if (--timeToGo == 0) {
+            return true;
+        }
+    }
+    return false;
+}