Apply IOMUX pull states to input pins so default PULL_UP/PULL_DOWN
values are reflected in GPIO_IN when pins are not driven. This
prevents gpio's being initialized low (until their value is set)
while actually configured as PULL_UP, for instance.

…ss bias

Original code expanded RGB565 to 8-bit channels, multiplied with truncating
division (/256), then shifted back — causing consistent darkening and minor
hue errors, especially noticeable at 40–80% brightness.

Improved version:
- Extracts components in native precision: 5-bit red/blue, 6-bit green
- Scales with proper rounding: (val * backlight + 127) >> 8
- Packs directly back to RGB565 format

Improves visual quality dramatically:
- Grays/whites stay neutral instead of going too dark or greenish
- Better preservation of shadow detail
- More natural fade-to-black behavior overall

Emulate the external pullup resistors on
the GPIO0/GPIO14 buttons of the T-Display-S3.

On the physical t-display-s3, this works:

pin0 = Pin(0, Pin.IN)
pin0.value() # returns 1 (as it should because it's pulled high by an external resistor)

But on the emulator, the same code behaves differently:

pin0 = Pin(0, Pin.IN)
pin0.value() # returns 0 because external pullups weren't emulated

Internal pullups have been implemented already in commit cbb15d7
at https://github.com/a159x36/qemu/pull/2/changes so this works:

pin0 = Pin(0, Pin.IN, Pin.PULL_UP)
pin0.value() # returns 1 when internal pullups are supported

Obviously, the more the emulator mimicks the real hardware, the better,
so this is another step in the right direction.