refactor: migrate complex-tooltip modules to ALabel dedup setters

Switch direct label_.set_markup/set_tooltip_markup calls to the
deduplicating setLabelMarkup/setTooltipMarkup helpers in clock, custom
and mpris, keeping their custom tooltip construction logic intact.
taskbar is left untouched: its tooltip lives on per-task Gtk::Button,
not on an ALabel label_.

src/modules/clock.cpp

@@ -162,7 +162,7 @@ auto waybar::modules::Clock::update() -> void {
   const auto* tz = tzList_[tzCurrIdx_] != nullptr ? tzList_[tzCurrIdx_] : local_zone();
   const zoned_time now{tz, floor<seconds>(system_clock::now())};
 
-  label_.set_markup(fmt_lib::vformat(m_locale_, format_, fmt_lib::make_format_args(now)));
+  setLabelMarkup(fmt_lib::vformat(m_locale_, format_, fmt_lib::make_format_args(now)));
 
   if (tooltipEnabled()) {
     const year_month_day today{floor<days>(now.get_local_time())};

src/modules/custom.cpp

@@ -187,7 +187,7 @@ auto waybar::modules::Custom::update() -> void {
       if ((config_["hide-empty-text"].asBool() && text_.empty()) || str.empty()) {
         event_box_.hide();
       } else {
-        label_.set_markup(str);
+        setLabelMarkup(str);
         if (tooltipEnabled()) {
           std::string tooltip_markup;
           if (tooltip_format_enabled_) {
@@ -202,10 +202,7 @@ auto waybar::modules::Custom::update() -> void {
             tooltip_markup = tooltip_;
           }
 
-          if (last_tooltip_markup_ != tooltip_markup) {
-            label_.set_tooltip_markup(tooltip_markup);
-            last_tooltip_markup_ = std::move(tooltip_markup);
-          }
+          setTooltipMarkup(tooltip_markup);
         }
         auto style = label_.get_style_context();
         auto classes = style->list_classes();

src/modules/mpris/mpris.cpp

@@ -735,7 +735,7 @@ auto Mpris::update() -> void {
     if (label_format.empty()) {
       label_.hide();
     } else {
-      label_.set_markup(label_format);
+      setLabelMarkup(label_format);
       label_.show();
     }
   } catch (fmt::format_error const& e) {
@@ -758,7 +758,7 @@ auto Mpris::update() -> void {
           fmt::arg("player_icon", getIconFromJson(config_["player-icons"], info.name)),
           fmt::arg("status_icon", getIconFromJson(config_["status-icons"], info.status_string)));
 
-      label_.set_tooltip_markup(tooltip_text);
+      setTooltipMarkup(tooltip_text);
     } catch (fmt::format_error const& e) {
       spdlog::warn("mpris: format error (tooltip): {}", e.what());
     }