feat: Seamless sleep/wake screens for displaying book pages during deep sleep (#2064)

<img width="605" height="454" alt="image"
src="https://github.com/user-attachments/assets/bfd84afe-3b58-436e-9a5d-539af3ec3d4e"
/>

Actualized "Last" sleep screen setting from previous PRs, rebranded as a
~~`Seamless Sleep`~~ `Page as Sleep Screen` option with more
improvements.


https://github.com/user-attachments/assets/59029ba6-007e-4841-abfa-f680d7e98b79

---

New option: `Page as Sleep Screen` - `Never (default)`, `After Timeout`,
`Always`

When enabled, it seamlessly sleeps on timeout or power off, making a
fast refresh for the moon icon. When waking up, we still show the last
page, instead of the boot screen, making it fully seamless.

I tried different icons such as "refresh arrow" and others, but they
looked not as nice as 3 simple dots.

With this mode, the device turns off 4 seconds faster. And has 6 seconds
less delay when turning back on. Much more responsive.

Previously, even a 10-minute timeout sometimes wasn't enough, and I'd
worry about seeing the book cover. It's now easier to use a shorter
sleep timeout: if I get distracted during a reading session but don't
want to stop, the new screen is much more inviting to come back to.

---

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

---

Test v1.3.0 firmware.bin file
[download](https://github.com/user-attachments/files/28015193/firmware.zip)

Based on PRs #410 and #495

Closes #400, #1649

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

src/activities/ActivityManager.cpp

@@ -196,8 +196,8 @@ void ActivityManager::goToReader(std::string path) {
   replaceActivity(std::make_unique<ReaderActivity>(renderer, mappedInput, std::move(path)));
 }
 
-void ActivityManager::goToSleep() {
-  replaceActivity(std::make_unique<SleepActivity>(renderer, mappedInput));
+void ActivityManager::goToSleep(bool fromTimeout) {
+  replaceActivity(std::make_unique<SleepActivity>(renderer, mappedInput, fromTimeout));
   loop();  // Important: sleep screen must be rendered immediately, the caller will go to sleep right after this returns
 }
 

src/activities/ActivityManager.h

@@ -86,7 +86,7 @@ class ActivityManager {
   void goToRecentBooks();
   void goToBrowser();
   void goToReader(std::string path);
-  void goToSleep();
+  void goToSleep(bool fromTimeout = false);
   void goToBoot();
   void goToFullScreenMessage(std::string message, EpdFontFamily::Style style = EpdFontFamily::REGULAR);
   void goToCrashReport();

src/activities/boot_sleep/SleepActivity.cpp

@@ -14,10 +14,20 @@
 #include "components/UITheme.h"
 #include "fontIds.h"
 #include "images/Logo120.h"
+#include "images/MoonIcon.h"
 
 void SleepActivity::onEnter() {
   Activity::onEnter();
 
+  const bool renderSeamless =
+      SETTINGS.seamlessSleepScreen == CrossPointSettings::SEAMLESS_SLEEP_SCREEN::SEAMLESS_ALWAYS ||
+      (fromTimeout &&
+       SETTINGS.seamlessSleepScreen == CrossPointSettings::SEAMLESS_SLEEP_SCREEN::SEAMLESS_AFTER_TIMEOUT);
+
+  if (renderSeamless) {
+    return renderLastScreenSleepScreen();
+  }
+
   // Show popup with reader orientation only when going to sleep from reader
   if (APP_STATE.lastSleepFromReader) {
     ReaderUtils::applyOrientation(renderer, SETTINGS.orientation);
@@ -307,6 +317,12 @@ void SleepActivity::renderCoverSleepScreen() const {
   return (this->*renderNoCoverSleepScreen)();
 }
 
+void SleepActivity::renderLastScreenSleepScreen() const {
+  const auto pageHeight = renderer.getScreenHeight();
+  renderer.drawImage(MoonIcon, 0, pageHeight - MOONICON_HEIGHT, MOONICON_WIDTH, MOONICON_HEIGHT);
+  renderer.displayBuffer(HalDisplay::HALF_REFRESH);
+}
+
 void SleepActivity::renderBlankSleepScreen() const {
   renderer.clearScreen();
   renderer.displayBuffer(HalDisplay::HALF_REFRESH);

src/activities/boot_sleep/SleepActivity.h

@@ -5,8 +5,8 @@ class Bitmap;
 
 class SleepActivity final : public Activity {
  public:
-  explicit SleepActivity(GfxRenderer& renderer, MappedInputManager& mappedInput)
-      : Activity("Sleep", renderer, mappedInput) {}
+  explicit SleepActivity(GfxRenderer& renderer, MappedInputManager& mappedInput, bool fromTimeout = false)
+      : Activity("Sleep", renderer, mappedInput), fromTimeout(fromTimeout) {}
   void onEnter() override;
 
  private:
@@ -14,5 +14,8 @@ class SleepActivity final : public Activity {
   void renderCustomSleepScreen() const;
   void renderCoverSleepScreen() const;
   void renderBitmapSleepScreen(const Bitmap& bitmap) const;
+  void renderLastScreenSleepScreen() const;
   void renderBlankSleepScreen() const;
+
+  bool fromTimeout = false;
 };