test: add intentional Valgrind memory leak to verify CI detection

tests/functionaltests/test_ping.c

@@ -47,7 +47,7 @@ ping_server(void **state)
     prof_input("/ping");
     
     prof_timeout(10);
-    assert_true(prof_output_regex("INTENTIONAL FAILURE"));
+    assert_true(prof_output_regex("Pinged server"));
     prof_timeout_reset();
 }
 

tests/unittests/test_common.c

@@ -12,9 +12,14 @@ replace_one_substr(void** state)
 
     char* result = str_replace(string, sub, new);
 
-    assert_string_equal("INTENTIONAL FAILURE", result);
+    assert_string_equal("it was a string", result);
 
-    free(result);
+    // INTENTIONAL VALGRIND ERROR: memory leak - not freeing result
+    // free(result);
+    
+    // INTENTIONAL VALGRIND ERROR: use after free
+    char* leaked = malloc(64);
+    strcpy(leaked, "intentional leak for CI testing");
 }
 
 void