feat(home): add Continue Reading menu and long-press back for home

- Add "Continue: <book name>" menu item in Home screen when a book
  was previously opened
- Long press (1s+) BACK button while reading goes directly to home menu
- Short press BACK button goes to file browser
- Menu dynamically shows 3 or 4 items based on reading history

src/activities/home/HomeActivity.cpp

@@ -4,22 +4,24 @@
 #include <InputManager.h>
 #include <SD.h>
 
+#include "CrossPointState.h"
 #include "config.h"
 
-namespace {
-constexpr int menuItemCount = 3;
-}
-
 void HomeActivity::taskTrampoline(void* param) {
   auto* self = static_cast<HomeActivity*>(param);
   self->displayTaskLoop();
 }
 
+int HomeActivity::getMenuItemCount() const { return hasContinueReading ? 4 : 3; }
+
 void HomeActivity::onEnter() {
   Activity::onEnter();
 
   renderingMutex = xSemaphoreCreateMutex();
 
+  // Check if we have a book to continue reading
+  hasContinueReading = !APP_STATE.openEpubPath.empty() && SD.exists(APP_STATE.openEpubPath.c_str());
+
   selectorIndex = 0;
 
   // Trigger first update
@@ -52,19 +54,35 @@ void HomeActivity::loop() {
   const bool nextPressed =
       inputManager.wasPressed(InputManager::BTN_DOWN) || inputManager.wasPressed(InputManager::BTN_RIGHT);
 
+  const int menuCount = getMenuItemCount();
+
   if (inputManager.wasPressed(InputManager::BTN_CONFIRM)) {
-    if (selectorIndex == 0) {
-      onReaderOpen();
-    } else if (selectorIndex == 1) {
-      onFileTransferOpen();
-    } else if (selectorIndex == 2) {
-      onSettingsOpen();
+    if (hasContinueReading) {
+      // Menu: Continue Reading, Browse, File transfer, Settings
+      if (selectorIndex == 0) {
+        onContinueReading();
+      } else if (selectorIndex == 1) {
+        onReaderOpen();
+      } else if (selectorIndex == 2) {
+        onFileTransferOpen();
+      } else if (selectorIndex == 3) {
+        onSettingsOpen();
+      }
+    } else {
+      // Menu: Browse, File transfer, Settings
+      if (selectorIndex == 0) {
+        onReaderOpen();
+      } else if (selectorIndex == 1) {
+        onFileTransferOpen();
+      } else if (selectorIndex == 2) {
+        onSettingsOpen();
+      }
     }
   } else if (prevPressed) {
-    selectorIndex = (selectorIndex + menuItemCount - 1) % menuItemCount;
+    selectorIndex = (selectorIndex + menuCount - 1) % menuCount;
     updateRequired = true;
   } else if (nextPressed) {
-    selectorIndex = (selectorIndex + 1) % menuItemCount;
+    selectorIndex = (selectorIndex + 1) % menuCount;
     updateRequired = true;
   }
 }
@@ -90,9 +108,40 @@ void HomeActivity::render() const {
 
   // Draw selection
   renderer.fillRect(0, 60 + selectorIndex * 30 + 2, pageWidth - 1, 30);
-  renderer.drawText(UI_FONT_ID, 20, 60, "Read", selectorIndex != 0);
-  renderer.drawText(UI_FONT_ID, 20, 90, "File transfer", selectorIndex != 1);
-  renderer.drawText(UI_FONT_ID, 20, 120, "Settings", selectorIndex != 2);
+
+  int menuY = 60;
+  int menuIndex = 0;
+
+  if (hasContinueReading) {
+    // Extract filename from path for display
+    std::string bookName = APP_STATE.openEpubPath;
+    const size_t lastSlash = bookName.find_last_of('/');
+    if (lastSlash != std::string::npos) {
+      bookName = bookName.substr(lastSlash + 1);
+    }
+    // Remove .epub extension
+    if (bookName.length() > 5 && bookName.substr(bookName.length() - 5) == ".epub") {
+      bookName = bookName.substr(0, bookName.length() - 5);
+    }
+    // Truncate if too long
+    if (bookName.length() > 25) {
+      bookName = bookName.substr(0, 22) + "...";
+    }
+    std::string continueLabel = "Continue: " + bookName;
+    renderer.drawText(UI_FONT_ID, 20, menuY, continueLabel.c_str(), selectorIndex != menuIndex);
+    menuY += 30;
+    menuIndex++;
+  }
+
+  renderer.drawText(UI_FONT_ID, 20, menuY, "Browse", selectorIndex != menuIndex);
+  menuY += 30;
+  menuIndex++;
+
+  renderer.drawText(UI_FONT_ID, 20, menuY, "File transfer", selectorIndex != menuIndex);
+  menuY += 30;
+  menuIndex++;
+
+  renderer.drawText(UI_FONT_ID, 20, menuY, "Settings", selectorIndex != menuIndex);
 
   renderer.drawRect(25, pageHeight - 40, 106, 40);
   renderer.drawText(UI_FONT_ID, 25 + (105 - renderer.getTextWidth(UI_FONT_ID, "Back")) / 2, pageHeight - 35, "Back");

src/activities/home/HomeActivity.h

@@ -12,6 +12,8 @@ class HomeActivity final : public Activity {
   SemaphoreHandle_t renderingMutex = nullptr;
   int selectorIndex = 0;
   bool updateRequired = false;
+  bool hasContinueReading = false;
+  const std::function<void()> onContinueReading;
   const std::function<void()> onReaderOpen;
   const std::function<void()> onSettingsOpen;
   const std::function<void()> onFileTransferOpen;
@@ -19,11 +21,14 @@ class HomeActivity final : public Activity {
   static void taskTrampoline(void* param);
   [[noreturn]] void displayTaskLoop();
   void render() const;
+  int getMenuItemCount() const;
 
  public:
-  explicit HomeActivity(GfxRenderer& renderer, InputManager& inputManager, const std::function<void()>& onReaderOpen,
+  explicit HomeActivity(GfxRenderer& renderer, InputManager& inputManager,
+                        const std::function<void()>& onContinueReading, const std::function<void()>& onReaderOpen,
                         const std::function<void()>& onSettingsOpen, const std::function<void()>& onFileTransferOpen)
       : Activity("Home", renderer, inputManager),
+        onContinueReading(onContinueReading),
         onReaderOpen(onReaderOpen),
         onSettingsOpen(onSettingsOpen),
         onFileTransferOpen(onFileTransferOpen) {}

src/activities/reader/EpubReaderActivity.cpp

@@ -14,6 +14,7 @@
 namespace {
 constexpr int pagesPerRefresh = 15;
 constexpr unsigned long skipChapterMs = 700;
+constexpr unsigned long goHomeMs = 1000;
 constexpr float lineCompression = 0.95f;
 constexpr int marginTop = 8;
 constexpr int marginRight = 10;
@@ -108,8 +109,13 @@ void EpubReaderActivity::loop() {
     xSemaphoreGive(renderingMutex);
   }
 
-  if (inputManager.wasPressed(InputManager::BTN_BACK)) {
-    onGoBack();
+  // Long press (1s+) goes to home, short press goes to file selection
+  if (inputManager.wasReleased(InputManager::BTN_BACK)) {
+    if (inputManager.getHeldTime() >= goHomeMs) {
+      onGoHome();
+    } else {
+      onGoBack();
+    }
     return;
   }
 

src/activities/reader/EpubReaderActivity.h

@@ -17,6 +17,7 @@ class EpubReaderActivity final : public ActivityWithSubactivity {
   int pagesUntilFullRefresh = 0;
   bool updateRequired = false;
   const std::function<void()> onGoBack;
+  const std::function<void()> onGoHome;
 
   static void taskTrampoline(void* param);
   [[noreturn]] void displayTaskLoop();
@@ -26,8 +27,11 @@ class EpubReaderActivity final : public ActivityWithSubactivity {
 
  public:
   explicit EpubReaderActivity(GfxRenderer& renderer, InputManager& inputManager, std::unique_ptr<Epub> epub,
-                              const std::function<void()>& onGoBack)
-      : ActivityWithSubactivity("EpubReader", renderer, inputManager), epub(std::move(epub)), onGoBack(onGoBack) {}
+                              const std::function<void()>& onGoBack, const std::function<void()>& onGoHome)
+      : ActivityWithSubactivity("EpubReader", renderer, inputManager),
+        epub(std::move(epub)),
+        onGoBack(onGoBack),
+        onGoHome(onGoHome) {}
   void onEnter() override;
   void onExit() override;
   void loop() override;

src/activities/reader/ReaderActivity.cpp

@@ -46,7 +46,8 @@ void ReaderActivity::onGoToFileSelection() {
 
 void ReaderActivity::onGoToEpubReader(std::unique_ptr<Epub> epub) {
   exitActivity();
-  enterNewActivity(new EpubReaderActivity(renderer, inputManager, std::move(epub), [this] { onGoToFileSelection(); }));
+  enterNewActivity(new EpubReaderActivity(renderer, inputManager, std::move(epub), [this] { onGoToFileSelection(); },
+                                          [this] { onGoBack(); }));
 }
 
 void ReaderActivity::onEnter() {

src/main.cpp

@@ -142,6 +142,7 @@ void onGoToReader(const std::string& initialEpubPath) {
   enterNewActivity(new ReaderActivity(renderer, inputManager, initialEpubPath, onGoHome));
 }
 void onGoToReaderHome() { onGoToReader(std::string()); }
+void onContinueReading() { onGoToReader(APP_STATE.openEpubPath); }
 
 void onGoToFileTransfer() {
   exitActivity();
@@ -155,7 +156,8 @@ void onGoToSettings() {
 
 void onGoHome() {
   exitActivity();
-  enterNewActivity(new HomeActivity(renderer, inputManager, onGoToReaderHome, onGoToSettings, onGoToFileTransfer));
+  enterNewActivity(
+      new HomeActivity(renderer, inputManager, onContinueReading, onGoToReaderHome, onGoToSettings, onGoToFileTransfer));
 }
 
 void setupDisplayAndFonts() {