Add icon generation script and list scroll helper

Introduce gen_icons.sh to regenerate UI icons from a manifest file using the FreeInk SDK's Lucide icon set. Add icons.manifest mapping UI icons to Lucide names. Refactor vertical swipe list scrolling into a reusable wasListScroll() helper method used by both reader chapter selection and settings activities. Add static assertion to ensure ThemeMetrics scaling stays in sync with struct changes.

src/activities/reader/XtcReaderChapterSelectionActivity.cpp

@@ -56,6 +56,12 @@ void XtcReaderChapterSelectionActivity::loop() {
   const int pageItems = getPageItems();
   const int totalItems = static_cast<int>(xtc->getChapters().size());
 
+  // Vertical swipe page-scrolls the list (touch nav without the side buttons).
+  if (mappedInput.wasListScroll(selectorIndex, totalItems, pageItems)) {
+    requestUpdate();
+    return;
+  }
+
   if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
     const auto& chapters = xtc->getChapters();
     if (!chapters.empty() && selectorIndex >= 0 && selectorIndex < static_cast<int>(chapters.size())) {

src/activities/settings/SettingsActivity.cpp

@@ -131,15 +131,11 @@ void SettingsActivity::loop() {
     hasChangedCategory = true;
     requestUpdate();
   } else if (swipe == MappedInputManager::SwipeDir::Up || swipe == MappedInputManager::SwipeDir::Down) {
-    // Vertical swipe scrolls the settings list a page at a time (touch navigation
-    // without the side buttons). Swipe up moves down the list, and vice versa.
+    // Vertical swipe page-scrolls the list (touch nav without the side buttons).
+    // count is settingsCount + 1 because row 0 is the category tab bar.
     const int page = std::max(
         1, UITheme::getNumberOfItemsPerPage(renderer, true, true, BaseTheme::showButtonHints(), false));
-    if (swipe == MappedInputManager::SwipeDir::Up) {
-      selectedSettingIndex = std::min(selectedSettingIndex + page, settingsCount);
-    } else {
-      selectedSettingIndex = std::max(selectedSettingIndex - page, 0);
-    }
+    mappedInput.wasListScroll(selectedSettingIndex, settingsCount + 1, page);
     requestUpdate();
   }