feat: unify navigation handling with system-wide continuous navigation (#600)

This PR unifies navigation handling & adds system-wide support for
continuous navigation.

## Summary
Holding down a navigation button now continuously advances through items
until the button is released. This removes the need for repeated
press-and-release actions and makes navigation faster and smoother,
especially in long menus or documents.

When page-based navigation is available, it will navigate through pages.
If not, it will progress through menu items or similar list-based UI
elements.

Additionally, this PR fixes inconsistencies in wrap-around behavior and
navigation index calculations.

Places where the navigation system was updated:
- Home Page
- Settings Pages
- My Library Page
- WiFi Selection Page
- OPDS Browser Page
- Keyboard
- File Transfer Page
- XTC Chapter Selector Page
- EPUB Chapter Selector Page

I’ve tested this on the device as much as possible and tried to match
the existing behavior. Please let me know if I missed anything. Thanks 🙏


![crosspoint](https://github.com/user-attachments/assets/6a3c7482-f45e-4a77-b156-721bb3b679e6)

---

Following the request from @osteotek and @daveallie for system-wide
support, the old PR (#379) has been closed in favor of this
consolidated, system-wide implementation.

---

### AI Usage

Did you use AI tools to help write this code? _**PARTIALLY**_

---------

Co-authored-by: Dave Allie <dave@daveallie.com>

src/activities/settings/SettingsActivity.cpp

@@ -16,10 +16,6 @@
 
 const char* SettingsActivity::categoryNames[categoryCount] = {"Display", "Reader", "Controls", "System"};
 
-namespace {
-constexpr int changeTabsMs = 700;
-}  // namespace
-
 void SettingsActivity::taskTrampoline(void* param) {
   auto* self = static_cast<SettingsActivity*>(param);
   self->displayTaskLoop();
@@ -116,28 +112,28 @@ void SettingsActivity::loop() {
     return;
   }
 
-  const bool upReleased = mappedInput.wasReleased(MappedInputManager::Button::Up);
-  const bool downReleased = mappedInput.wasReleased(MappedInputManager::Button::Down);
-  const bool leftReleased = mappedInput.wasReleased(MappedInputManager::Button::Left);
-  const bool rightReleased = mappedInput.wasReleased(MappedInputManager::Button::Right);
-  const bool changeTab = mappedInput.getHeldTime() > changeTabsMs;
-
   // Handle navigation
-  if (upReleased && changeTab) {
+  buttonNavigator.onNextRelease([this] {
+    selectedSettingIndex = ButtonNavigator::nextIndex(selectedSettingIndex, settingsCount + 1);
+    updateRequired = true;
+  });
+
+  buttonNavigator.onPreviousRelease([this] {
+    selectedSettingIndex = ButtonNavigator::previousIndex(selectedSettingIndex, settingsCount + 1);
+    updateRequired = true;
+  });
+
+  buttonNavigator.onNextContinuous([this, &hasChangedCategory] {
     hasChangedCategory = true;
-    selectedCategoryIndex = (selectedCategoryIndex > 0) ? (selectedCategoryIndex - 1) : (categoryCount - 1);
+    selectedCategoryIndex = ButtonNavigator::nextIndex(selectedCategoryIndex, categoryCount);
     updateRequired = true;
-  } else if (downReleased && changeTab) {
+  });
+
+  buttonNavigator.onPreviousContinuous([this, &hasChangedCategory] {
     hasChangedCategory = true;
-    selectedCategoryIndex = (selectedCategoryIndex < categoryCount - 1) ? (selectedCategoryIndex + 1) : 0;
+    selectedCategoryIndex = ButtonNavigator::previousIndex(selectedCategoryIndex, categoryCount);
     updateRequired = true;
-  } else if (upReleased || leftReleased) {
-    selectedSettingIndex = (selectedSettingIndex > 0) ? (selectedSettingIndex - 1) : (settingsCount);
-    updateRequired = true;
-  } else if (rightReleased || downReleased) {
-    selectedSettingIndex = (selectedSettingIndex < settingsCount) ? (selectedSettingIndex + 1) : 0;
-    updateRequired = true;
-  }
+  });
 
   if (hasChangedCategory) {
     selectedSettingIndex = (selectedSettingIndex == 0) ? 0 : 1;