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/util/KeyboardEntryActivity.cpp

@@ -142,37 +142,24 @@ void KeyboardEntryActivity::handleKeyPress() {
 }
 
 void KeyboardEntryActivity::loop() {
-  // Navigation
-  if (mappedInput.wasPressed(MappedInputManager::Button::Up)) {
-    if (selectedRow > 0) {
-      selectedRow--;
-      // Clamp column to valid range for new row
-      const int maxCol = getRowLength(selectedRow) - 1;
-      if (selectedCol > maxCol) selectedCol = maxCol;
-    } else {
-      // Wrap to bottom row
-      selectedRow = NUM_ROWS - 1;
-      const int maxCol = getRowLength(selectedRow) - 1;
-      if (selectedCol > maxCol) selectedCol = maxCol;
-    }
-    updateRequired = true;
-  }
+  // Handle navigation
+  buttonNavigator.onPressAndContinuous({MappedInputManager::Button::Up}, [this] {
+    selectedRow = ButtonNavigator::previousIndex(selectedRow, NUM_ROWS);
 
-  if (mappedInput.wasPressed(MappedInputManager::Button::Down)) {
-    if (selectedRow < NUM_ROWS - 1) {
-      selectedRow++;
-      const int maxCol = getRowLength(selectedRow) - 1;
-      if (selectedCol > maxCol) selectedCol = maxCol;
-    } else {
-      // Wrap to top row
-      selectedRow = 0;
-      const int maxCol = getRowLength(selectedRow) - 1;
-      if (selectedCol > maxCol) selectedCol = maxCol;
-    }
+    const int maxCol = getRowLength(selectedRow) - 1;
+    if (selectedCol > maxCol) selectedCol = maxCol;
     updateRequired = true;
-  }
+  });
 
-  if (mappedInput.wasPressed(MappedInputManager::Button::Left)) {
+  buttonNavigator.onPressAndContinuous({MappedInputManager::Button::Down}, [this] {
+    selectedRow = ButtonNavigator::nextIndex(selectedRow, NUM_ROWS);
+
+    const int maxCol = getRowLength(selectedRow) - 1;
+    if (selectedCol > maxCol) selectedCol = maxCol;
+    updateRequired = true;
+  });
+
+  buttonNavigator.onPressAndContinuous({MappedInputManager::Button::Left}, [this] {
     const int maxCol = getRowLength(selectedRow) - 1;
 
     // Special bottom row case
@@ -191,20 +178,14 @@ void KeyboardEntryActivity::loop() {
         // At done button, move to backspace
         selectedCol = BACKSPACE_COL;
       }
-      updateRequired = true;
-      return;
-    }
-
-    if (selectedCol > 0) {
-      selectedCol--;
     } else {
-      // Wrap to end of current row
-      selectedCol = maxCol;
+      selectedCol = ButtonNavigator::previousIndex(selectedCol, maxCol + 1);
     }
-    updateRequired = true;
-  }
 
-  if (mappedInput.wasPressed(MappedInputManager::Button::Right)) {
+    updateRequired = true;
+  });
+
+  buttonNavigator.onPressAndContinuous({MappedInputManager::Button::Right}, [this] {
     const int maxCol = getRowLength(selectedRow) - 1;
 
     // Special bottom row case
@@ -223,18 +204,11 @@ void KeyboardEntryActivity::loop() {
         // At done button, wrap to beginning of row
         selectedCol = SHIFT_COL;
       }
-      updateRequired = true;
-      return;
-    }
-
-    if (selectedCol < maxCol) {
-      selectedCol++;
     } else {
-      // Wrap to beginning of current row
-      selectedCol = 0;
+      selectedCol = ButtonNavigator::nextIndex(selectedCol, maxCol + 1);
     }
     updateRequired = true;
-  }
+  });
 
   // Selection
   if (mappedInput.wasPressed(MappedInputManager::Button::Confirm)) {