feat: X3 clock display with DS3231 RTC and NTP sync (#1612)

src/activities/settings/ClockOffsetActivity.h

@@ -0,0 +1,37 @@
+#pragma once
+
+#include "activities/Activity.h"
+#include "util/ButtonNavigator.h"
+
+// Dedicated UTC offset picker for the status bar clock.
+// Three editable fields (sign, hours, minutes); Confirm cycles fields, Up/Down adjust the active one.
+// Supports the full IANA UTC offset range in 15 minute steps, including oddball zones like Nepal (+5:45).
+class ClockOffsetActivity final : public Activity {
+ public:
+  explicit ClockOffsetActivity(GfxRenderer& renderer, MappedInputManager& mappedInput)
+      : Activity("ClockOffset", renderer, mappedInput) {}
+
+  void onEnter() override;
+  void onExit() override;
+  void loop() override;
+  void render(RenderLock&&) override;
+
+ private:
+  ButtonNavigator buttonNavigator;
+
+  enum Field { FIELD_SIGN = 0, FIELD_HOURS = 1, FIELD_MINUTES = 2, FIELD_COUNT };
+  Field activeField = FIELD_HOURS;
+
+  // Working copy of the offset, edited in-place. Saved back to SETTINGS on exit.
+  // 0 = positive offset, 1 = negative offset.
+  uint8_t sign = 0;
+  // Hours: 0..14 when positive, 0..12 when negative.
+  uint8_t hours = 0;
+  // Quarter-hour index 0..3 (0, 15, 30, 45).
+  uint8_t minutesQuarter = 0;
+
+  void loadFromSettings();
+  void saveToSettings() const;
+  void adjustActiveField(int delta);
+  void clampForSign();
+};