feat: add Time to Sleep user preference setting

Add configurable auto-sleep timeout in Settings with options:
- 1 minute
- 5 minutes
- 10 minutes (default)
- 15 minutes
- 30 minutes

Changes:
- Add SLEEP_TIMEOUT enum and sleepTimeout field to CrossPointSettings
- Add getSleepTimeoutMs() helper method
- Add sleepTimeout to settings serialization
- Add 'Time to Sleep' option in SettingsActivity
- Replace hardcoded AUTO_SLEEP_TIMEOUT_MS with SETTINGS.getSleepTimeoutMs()

src/CrossPointSettings.cpp

@@ -12,7 +12,7 @@ CrossPointSettings CrossPointSettings::instance;
 namespace {
 constexpr uint8_t SETTINGS_FILE_VERSION = 1;
 // Increment this when adding new persisted settings fields
-constexpr uint8_t SETTINGS_COUNT = 11;
+constexpr uint8_t SETTINGS_COUNT = 12;
 constexpr char SETTINGS_FILE[] = "/.crosspoint/settings.bin";
 }  // namespace
 
@@ -38,6 +38,7 @@ bool CrossPointSettings::saveToFile() const {
   serialization::writePod(outputFile, fontSize);
   serialization::writePod(outputFile, lineSpacing);
   serialization::writePod(outputFile, paragraphAlignment);
+  serialization::writePod(outputFile, sleepTimeout);
   outputFile.close();
 
   Serial.printf("[%lu] [CPS] Settings saved to file\n", millis());
@@ -86,6 +87,8 @@ bool CrossPointSettings::loadFromFile() {
     if (++settingsRead >= fileSettingsCount) break;
     serialization::readPod(inputFile, paragraphAlignment);
     if (++settingsRead >= fileSettingsCount) break;
+    serialization::readPod(inputFile, sleepTimeout);
+    if (++settingsRead >= fileSettingsCount) break;
   } while (false);
 
   inputFile.close();
@@ -129,6 +132,22 @@ float CrossPointSettings::getReaderLineCompression() const {
   }
 }
 
+unsigned long CrossPointSettings::getSleepTimeoutMs() const {
+  switch (sleepTimeout) {
+    case SLEEP_1_MIN:
+      return 1UL * 60 * 1000;
+    case SLEEP_5_MIN:
+      return 5UL * 60 * 1000;
+    case SLEEP_10_MIN:
+    default:
+      return 10UL * 60 * 1000;
+    case SLEEP_15_MIN:
+      return 15UL * 60 * 1000;
+    case SLEEP_30_MIN:
+      return 30UL * 60 * 1000;
+  }
+}
+
 int CrossPointSettings::getReaderFontId() const {
   switch (fontFamily) {
     case BOOKERLY:

src/CrossPointSettings.h

@@ -45,6 +45,9 @@ class CrossPointSettings {
   enum LINE_COMPRESSION { TIGHT = 0, NORMAL = 1, WIDE = 2 };
   enum PARAGRAPH_ALIGNMENT { JUSTIFIED = 0, LEFT_ALIGN = 1, CENTER_ALIGN = 2, RIGHT_ALIGN = 3 };
 
+  // Auto-sleep timeout options (in minutes)
+  enum SLEEP_TIMEOUT { SLEEP_1_MIN = 0, SLEEP_5_MIN = 1, SLEEP_10_MIN = 2, SLEEP_15_MIN = 3, SLEEP_30_MIN = 4 };
+
   // Sleep screen settings
   uint8_t sleepScreen = DARK;
   // Status bar settings
@@ -64,6 +67,8 @@ class CrossPointSettings {
   uint8_t fontSize = MEDIUM;
   uint8_t lineSpacing = NORMAL;
   uint8_t paragraphAlignment = JUSTIFIED;
+  // Auto-sleep timeout setting (default 10 minutes)
+  uint8_t sleepTimeout = SLEEP_10_MIN;
 
   ~CrossPointSettings() = default;
 
@@ -77,6 +82,7 @@ class CrossPointSettings {
   bool loadFromFile();
 
   float getReaderLineCompression() const;
+  unsigned long getSleepTimeoutMs() const;
 };
 
 // Helper macro to access settings

src/activities/settings/SettingsActivity.cpp

@@ -38,6 +38,7 @@ const SettingInfo settingsList[settingsCount] = {
      SettingType::ENUM,
      &CrossPointSettings::paragraphAlignment,
      {"Justify", "Left", "Center", "Right"}},
+    {"Time to Sleep", SettingType::ENUM, &CrossPointSettings::sleepTimeout, {"1 min", "5 min", "10 min", "15 min", "30 min"}},
     {"Check for updates", SettingType::ACTION, nullptr, {}},
 };
 }  // namespace

src/main.cpp

@@ -126,8 +126,6 @@ EpdFont ui12RegularFont(&ubuntu_12_regular);
 EpdFont ui12BoldFont(&ubuntu_12_bold);
 EpdFontFamily ui12FontFamily(&ui12RegularFont, &ui12BoldFont);
 
-// Auto-sleep timeout (10 minutes of inactivity)
-constexpr unsigned long AUTO_SLEEP_TIMEOUT_MS = 10 * 60 * 1000;
 // measurement of power button press duration calibration value
 unsigned long t1 = 0;
 unsigned long t2 = 0;
@@ -323,8 +321,9 @@ void loop() {
     lastActivityTime = millis();  // Reset inactivity timer
   }
 
-  if (millis() - lastActivityTime >= AUTO_SLEEP_TIMEOUT_MS) {
-    Serial.printf("[%lu] [SLP] Auto-sleep triggered after %lu ms of inactivity\n", millis(), AUTO_SLEEP_TIMEOUT_MS);
+  const unsigned long sleepTimeoutMs = SETTINGS.getSleepTimeoutMs();
+  if (millis() - lastActivityTime >= sleepTimeoutMs) {
+    Serial.printf("[%lu] [SLP] Auto-sleep triggered after %lu ms of inactivity\n", millis(), sleepTimeoutMs);
     enterDeepSleep();
     // This should never be hit as `enterDeepSleep` calls esp_deep_sleep_start
     return;