feat(nav): add jump-to-page feature and progress percentage

Adds comprehensive navigation improvements:

**Jump to Page Feature:**
- Add "Jump to Page Number" menu item in book parameters menu
- Implement UINT16 form for page number input with validation
- Add get_page_id_from_page_nbr() method to PageLocs for efficient lookup
- Navigate to target page with proper error handling
- Show helpful message if pages are still being computed

**Progress Display Enhancement:**
- Add percentage indicator to page display (e.g., "25 / 150 (16%)")
- Calculate and show reading progress at screen bottom
- Improves user awareness of position in book

**Technical Details:**
- Uses existing FormViewer infrastructure for input
- Thread-safe PageLocs lookup with mutex protection
- Proper 1-based to 0-based page number conversion
- Clean separation of concerns with new helper method
- Zero memory allocations (uses stack-based lookups)

Testing:
- Builds successfully for Paper S3 target
- Firmware flashed and verified on device
- Menu integration tested
- Form validation tested

Closes turgu1#3 (navigation improvements)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: murrain

get-platformio.py

@@ -13,12 +13,14 @@ class BookParamController
     static constexpr char const * TAG = "BookParamController";
 
     bool book_params_form_is_shown;
+    bool jump_to_page_form_is_shown;
     bool wait_for_key_after_wifi;
     bool delete_current_book;
 
   public:
-    BookParamController() : 
-      book_params_form_is_shown(false), 
+    BookParamController() :
+      book_params_form_is_shown(false),
+      jump_to_page_form_is_shown(false),
         wait_for_key_after_wifi(false),
             delete_current_book(false) { };
 
@@ -27,9 +29,10 @@ class BookParamController
     void          leave(bool going_to_deep_sleep = false);
     void set_font_count(uint8_t count);
 
-    inline void set_book_params_form_is_shown() { book_params_form_is_shown = true; }
-    inline void   set_wait_for_key_after_wifi() { wait_for_key_after_wifi   = true; }
-    inline void       set_delete_current_book() { delete_current_book       = true; }
+    inline void    set_book_params_form_is_shown() { book_params_form_is_shown    = true; }
+    inline void set_jump_to_page_form_is_shown() { jump_to_page_form_is_shown = true; }
+    inline void      set_wait_for_key_after_wifi() { wait_for_key_after_wifi      = true; }
+    inline void          set_delete_current_book() { delete_current_book          = true; }
 };
 
 #if __BOOK_PARAM_CONTROLLER__

include/controllers/book_param_controller.hpp

@@ -159,10 +159,26 @@ class PageLocs
 
     inline int16_t get_page_nbr(const PageId & id) {
       std::scoped_lock guard(mutex);
-      if (!completed) return -1; 
+      if (!completed) return -1;
       const PageInfo * info = get_page_info(id);
       return info == nullptr ? -1 : info->page_number;
     };
+
+    /**
+     * @brief Get PageId from page number (0-based)
+     * @param page_nbr The page number (0-based)
+     * @return Pointer to PageId if found, nullptr otherwise
+     */
+    inline const PageId * get_page_id_from_page_nbr(int16_t page_nbr) {
+      std::scoped_lock guard(mutex);
+      if (!completed) return nullptr;
+      for (const auto & entry : pages_map) {
+        if (entry.second.page_number == page_nbr) {
+          return &entry.first;
+        }
+      }
+      return nullptr;
+    };
 };
 
 #if __PAGE_LOCS__

include/models/page_locs.hpp

@@ -17,6 +17,7 @@
 #include "viewers/menu_viewer.hpp"
 #include "viewers/form_viewer.hpp"
 #include "viewers/msg_viewer.hpp"
+#include "viewers/book_viewer.hpp"
 
 #if EPUB_INKPLATE_BUILD && !BOARD_TYPE_PAPER_S3
   #include "esp_system.h"
@@ -189,21 +190,66 @@ wifi_mode()
 static void
 power_off()
 {
-  books_dir_controller.save_last_book(book_controller.get_current_page_id(), true); 
-  
+  books_dir_controller.save_last_book(book_controller.get_current_page_id(), true);
+
   CommonActions::power_it_off();
 }
 
+// Jump to page functionality
+static uint16_t target_page_number = 1;
+
+static FormEntry jump_to_page_form_entry = {
+  .caption = "Page Number:",
+  .u = { .val = { .value = &target_page_number,
+                  .min   = 1,
+                  .max   = 1 } }, // max will be updated dynamically
+  .entry_type = FormEntryType::UINT16
+};
+
+static void
+jump_to_page()
+{
+  int16_t page_count = page_locs.get_page_count();
+
+  if (page_count <= 0) {
+    msg_viewer.show(MsgViewer::MsgType::INFO,
+                    false, false,
+                    "Jump to Page",
+                    "Pages are still being computed. Please wait.");
+    return;
+  }
+
+  // Get current page for default value
+  const PageLocs::PageId & current_page_id = book_controller.get_current_page_id();
+  int16_t current_page = page_locs.get_page_nbr(current_page_id);
+  if (current_page >= 0) {
+    target_page_number = static_cast<uint16_t>(current_page + 1); // +1 because UI shows 1-based
+  }
+  else {
+    target_page_number = 1;
+  }
+
+  // Update form max value to actual page count
+  jump_to_page_form_entry.u.val.max = static_cast<uint16_t>(page_count);
+
+  // Show the form
+  form_viewer.show(&jump_to_page_form_entry, 1,
+                   "(Enter page number to jump to)");
+
+  book_param_controller.set_jump_to_page_form_is_shown();
+}
+
 // IMPORTANT!!
 // The first (menu[0]) and the last menu entry (the one before END_MENU) MUST ALWAYS BE VISIBLE!!!
 
-static MenuViewer::MenuEntry menu[10] = {
+static MenuViewer::MenuEntry menu[11] = {
   { MenuViewer::Icon::RETURN,      "Return to the e-books reader",         CommonActions::return_to_last, true , true },
   { MenuViewer::Icon::TOC,         "Table of Content",                     toc_ctrl                     , false, true },
+  { MenuViewer::Icon::BOOK,        "Jump to Page Number",                  jump_to_page                 , true , true },
   { MenuViewer::Icon::BOOK_LIST,   "E-Books list",                         books_list                   , true , true },
   { MenuViewer::Icon::FONT_PARAMS, "Current e-book parameters",            book_parameters              , true , true },
   { MenuViewer::Icon::REVERT,      "Revert e-book parameters to "
-                                   "default values",                       revert_to_defaults           , true , true },  
+                                   "default values",                       revert_to_defaults           , true , true },
   { MenuViewer::Icon::DELETE,      "Delete the current e-book",            delete_book                  , true , true },
   { MenuViewer::Icon::WIFI,        "WiFi Access to the e-books folder",    wifi_mode                    , true , true },
   { MenuViewer::Icon::INFO,        "About the EPub-InkPlate application",  CommonActions::about         , true , true },
@@ -266,6 +312,35 @@ BookParamController::input_event(const EventMgr::Event & event)
       menu_viewer.clear_highlight();
     }
   }
+  else if (jump_to_page_form_is_shown) {
+    if (form_viewer.event(event)) {
+      jump_to_page_form_is_shown = false;
+
+      // Convert page number (1-based) to 0-based for internal use
+      int16_t target_page_nbr = static_cast<int16_t>(target_page_number) - 1;
+
+      // Find the PageId that corresponds to this page number
+      const PageLocs::PageId * page_id_ptr = page_locs.get_page_id_from_page_nbr(target_page_nbr);
+
+      if (page_id_ptr != nullptr) {
+        // Navigate to the target page
+        book_controller.set_current_page_id(*page_id_ptr);
+        book_viewer.show_page(*page_id_ptr);
+
+        // Return to book reading
+        app_controller.set_controller(AppController::Ctrl::BOOK);
+      }
+      else {
+        msg_viewer.show(MsgViewer::MsgType::INFO,
+                        false, false,
+                        "Jump to Page",
+                        "Page %d could not be found. Please try again.",
+                        target_page_number);
+      }
+
+      menu_viewer.clear_highlight();
+    }
+  }
   else if (delete_current_book) {
     bool ok;
     if (msg_viewer.confirm(event, ok)) {

src/controllers/book_param_controller.cpp

@@ -54,11 +54,14 @@ ScreenBottom::show(int16_t page_nbr, int16_t page_count)
                     Pos(0, Screen::get_height() - h));
 
   if ((page_nbr != -1) && (page_count != -1)) {
-    ostr << page_nbr + 1 << " / " << page_count;
+    // Calculate percentage
+    int percentage = (page_count > 0) ? ((page_nbr + 1) * 100 / page_count) : 0;
 
-    page.put_str_at(ostr.str(), 
-                    Pos(Page::HORIZONTAL_CENTER, 
-                        Screen::get_height() + font->get_descender_height(FONT_SIZE) - 2), 
+    ostr << page_nbr + 1 << " / " << page_count << "  (" << percentage << "%)";
+
+    page.put_str_at(ostr.str(),
+                    Pos(Page::HORIZONTAL_CENTER,
+                        Screen::get_height() + font->get_descender_height(FONT_SIZE) - 2),
                     fmt);
   }