fix: use sleep routine from the original firmware (#1298)

## Summary

Fixes #1263

I spent half of my day(-off) reverse engineering the stock english
firmware V3.1.1, it's more or less like solving a sudoku with some known
pieces (like debug strings, known static addresses, known compiled
function, etc) and then the task is to guess the rest.

Long story short, this is the sleep routine that they use:

<img width="674" height="604" alt="image"
src="https://github.com/user-attachments/assets/6d53ce44-7bae-40c7-b4fb-24f898dbcc05"
/>

From the code above:
- They pull down GPIO13 (value = 0xd) before sleep
- They verify that power button is released by doing a delay loop of
50ms, similar to what we're doing
- `esp_sleep_config_gpio_isolate` is called but I'm not 100% sure why
- Pull up power button, note that it's likely redundant because power
button should already pulled up by `InputManager`
- `param1` and `param2` means enabling front/side buttons for wake up,
but it doesn't used in the code in reality. But I think it's physically
impossible, see the explanation below
- `param3` means "wake up from power button"
- `esp_sleep_start` is used; there is a logic to handle if it fails to
sleep, then retry recursively (no idea why!)

My observation is that they use GPIO13 so that it will be on HIGH state
when the chip is powered on, without any user space code to keep it on
that state. And once going to deep sleep, it goes into FLOATING by
default. That may explain why it need to be in LOW state before going to
sleep. (Nice trick btw)

Looking again at the circuit diagram provided
[here](https://github.com/sunwoods/Xteink-X4/blob/main/readme-img/sch.jpg)
(note: it's not official):

<img width="705" height="384" alt="image"
src="https://github.com/user-attachments/assets/b98d59fd-47ca-4d3d-a24a-94bf999e957b"
/>

It kinda make sense as the GPIO13 and VBUS (USB VCC) have the same role,
they are part of a simple "battery protection" cirtuit

Now, we may wonder, how the device wake up when there is no battery at
all?

<img width="440" height="323" alt="image"
src="https://github.com/user-attachments/assets/2981c411-239b-49a7-b9f7-9a75b6c1b6d3"
/>

It seems like power button is not just a simple switch between GPIO3 and
ground, but it also linked the POWER_CTRL, which leads to nowhere on the
diagram, but I suppose it connects the battery back for a short amount
of time, just enough for the MCU to wake up, and GPIO13 goes HIGH again.
It may also explain why power button becomes non-responsive for ~1
second after power on, as it's being pulled up by the current from
battery (remind: high = not pressed, low = pressed)

To test the theory above, I simply **comment out** the
`esp_deep_sleep_enable_gpio_wakeup`:
- On battery, power button works as nothing happen
- On USB, it doesn't wake up, I need to press RST

---

Important things about my analysis:
1. I had to name every function on the code above **manually**, but I'm
99% confident about it. The only function that I'm not sure is
`esp_wifi_bt_power_domain_off` ; Edit: it was indeed mislabeled, see
https://github.com/crosspoint-reader/crosspoint-reader/pull/1298#discussion_r2879670852
2. Some logic inside the stock firmware looks very strange, there is
almost no mention to "arduino" in the hardware, suggesting that they may
just call esp-idf functions directly, bypassing the arduino abstraction.

---

### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? **NO**

---------

Co-authored-by: Zach Nelson <zach@zdnelson.com>

lib/hal/HalPowerManager.cpp

@@ -58,7 +58,20 @@ void HalPowerManager::startDeepSleep(HalGPIO& gpio) const {
     delay(50);
     gpio.update();
   }
+  // Pre-sleep routines from the original firmware
+  // GPIO13 is connected to battery latch MOSFET, we need to make sure it's low during sleep
+  // Note that this means the MCU will be completely powered off during sleep, including RTC
+  constexpr gpio_num_t GPIO_SPIWP = GPIO_NUM_13;
+  gpio_set_direction(GPIO_SPIWP, GPIO_MODE_OUTPUT);
+  gpio_set_level(GPIO_SPIWP, 0);
+  esp_sleep_config_gpio_isolate();
+  gpio_deep_sleep_hold_en();
+  gpio_hold_en(GPIO_SPIWP);
+  pinMode(InputManager::POWER_BUTTON_PIN, INPUT_PULLUP);
   // Arm the wakeup trigger *after* the button is released
+  // Note: this is only useful for waking up on USB power. On battery, the MCU will be completely powered off, so the
+  // power button is hard-wired to briefly provide power to the MCU, waking it up regardless of the wakeup source
+  // configuration
   esp_deep_sleep_enable_gpio_wakeup(1ULL << InputManager::POWER_BUTTON_PIN, ESP_GPIO_WAKEUP_GPIO_LOW);
   // Enter Deep Sleep
   esp_deep_sleep_start();