fix: use power button held time for shutdown logic (#1890)

## Summary

* **What is the goal of this PR?**
Fix incorrect power button long-press detection during shutdown/wake
verification by introducing dedicated power button timing logic.
* **What changes are included?**
* Added getPowerButtonHeldTime() to HalGPIO as a wrapper over input
manager logic
* Replaced generic getHeldTime() usage with power-button-specific timing
in verifyPowerButtonWakeup()
* Ensures shutdown/wake decision is based only on actual power button
hold duration, not any-button timing
  * Minor header update for new API exposure in HalGPIO.h
## Additional Context

This fixes a bug where holding another button while briefly pressing the
power button could incorrectly trigger shutdown behavior due to shared
timing state (getHeldTime()).

The change isolates power button timing to prevent cross-button
interference and makes shutdown logic reliable during multi-button
interactions.

No behavioral changes are expected outside of power-button handling
logic.

**Dependencies**
- SDK PR: https://github.com/crosspoint-reader/community-sdk/pull/3

This PR requires the `community-sdk` submodule to be updated after the
SDK change is merged.

- Fixes: #1881

---

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

src/main.cpp

@@ -185,8 +185,8 @@ void verifyPowerButtonDuration() {
     do {
       delay(10);
       gpio.update();
-    } while (gpio.isPressed(HalGPIO::BTN_POWER) && gpio.getHeldTime() < calibratedPressDuration);
-    abort = gpio.getHeldTime() < calibratedPressDuration;
+    } while (gpio.isPressed(HalGPIO::BTN_POWER) && gpio.getPowerButtonHeldTime() < calibratedPressDuration);
+    abort = gpio.getPowerButtonHeldTime() < calibratedPressDuration;
   } else {
     abort = true;
   }
@@ -461,7 +461,7 @@ void loop() {
     return;
   }
 
-  if (gpio.isPressed(HalGPIO::BTN_POWER) && gpio.getHeldTime() > SETTINGS.getPowerButtonDuration()) {
+  if (gpio.isPressed(HalGPIO::BTN_POWER) && gpio.getPowerButtonHeldTime() > SETTINGS.getPowerButtonDuration()) {
     // If the screenshot combination is potentially being pressed, don't sleep
     if (gpio.isPressed(HalGPIO::BTN_DOWN)) {
       return;