Add InkHUD driver for WeAct Studio 4.2" display module (#6384)

* chore: todo.txt

* chore: InkHUD documentation
Word salad for maintainers

* refactor: don't init system applets using onActivate
System applets cannot be deactivated, so we will avoid using onActivate / onDeactivate methods entirely.

* chore: update the example applets

* fix: SSD16XX reset pulse
Allow time for controller IC to wake. Aligns with manufacturer's suggestions.
T-Echo button timing adjusted to prevent bouncing as a result(?) of slightly faster refreshes.

* fix: allow timeout if display update fails
Result is not graceful, but avoids total display lockup requiring power cycle.
Typical cause of failure is poor wiring / power supply.

* fix: improve display health on shutdown
Two extra full refreshes, masquerading as a "shutting down" screen. One is drawn white-on-black, to really shake the pixels up.

* feat: driver for display HINK_E042A87
As of Feb. 2025, these panels are used for "WeActStudio 4.2in B&W" display modules.

* fix: inkhud rotation should default to 0

* Revert "chore: todo.txt"

This reverts commit bea7df44a7.

* fix: more generous timeout for display updates
Previously this was tied to the expected duration of the update, but this didn't account for any delay if our polling thread got held up by an unrelated firmware task.

* fix: don't use the full shutdown screen during reboot

* fix: cooldown period during the display shutdown display sequence
Observed to prevent border pixels from being locked in place with some residual charge?

src/graphics/niche/Drivers/EInk/EInk.cpp

@@ -6,7 +6,7 @@ using namespace NicheGraphics::Drivers;
 
 // Separate from EInk::begin method, as derived class constructors can probably supply these parameters as constants
 EInk::EInk(uint16_t width, uint16_t height, UpdateTypes supported)
-    : concurrency::OSThread("E-Ink Driver"), width(width), height(height), supportedUpdateTypes(supported)
+    : concurrency::OSThread("EInkDriver"), width(width), height(height), supportedUpdateTypes(supported)
 {
     OSThread::disable();
 }
@@ -31,8 +31,8 @@ bool EInk::supports(UpdateTypes type)
 void EInk::beginPolling(uint32_t interval, uint32_t expectedDuration)
 {
     updateRunning = true;
-    updateBegunAt = millis();
     pollingInterval = interval;
+    pollingBegunAt = millis();
 
     // To minimize load, we can choose to delay polling for a few seconds, if we know roughly how long the update will take
     // By default, expectedDuration is 0, and we'll start polling immediately
@@ -45,10 +45,26 @@ void EInk::beginPolling(uint32_t interval, uint32_t expectedDuration)
 // This is what allows us to update the display asynchronously
 int32_t EInk::runOnce()
 {
+    // Check for polling timeout
+    // Manually set at 10 seconds, in case some big task holds up the firmware's cooperative multitasking
+    if (millis() - pollingBegunAt > 10000)
+        failed = true;
+
+    // Handle failure
+    // - polling timeout
+    // - other error (derived classes)
+    if (failed) {
+        LOG_WARN("Display update failed. Check wiring & power supply.");
+        updateRunning = false;
+        failed = false;
+        return disable();
+    }
+
+    // If update not yet done
     if (!isUpdateDone())
         return pollingInterval; // Poll again in a few ms
 
-    // If update done:
+    // If update done
     finalizeUpdate();      // Any post-update code: power down panel hardware, hibernate, etc
     updateRunning = false; // Change what we report via EInk::busy()
     return disable();      // Stop polling