Add automatic temperature sensor selection for daemon

[leonardoman9]

Summary

Adds an optional automatic temperature sensor selection mode for the daemon:

epomakercontroller start-daemon --auto-temp

When enabled, the daemon chooses a temperature sensor automatically instead of requiring users to
manually inspect list-temp-devices and pass a key such as coretemp-0.

The selection policy is conservative:

• prefer CPU/SoC sensors such as coretemp, k10temp, zenpower, cpu_thermal, soc_thermal, acpitz
• then fall back to other non-GPU sensors
• use GPU sensors only if no better sensor is available

This avoids choosing NVIDIA/AMD GPU sensors by default, since repeated GPU sensor polling can be more
disruptive on some systems.

Changes

• Add --auto-temp to start-daemon
• Add select_temp_device() in utils/sensors.py
• Mark the automatically selected sensor with * in list-temp-devices
• Add tests for automatic sensor selection
• Update README with the new usage
• Fix formatting in list-temp-devices
• Resolve default config paths independent of the current working directory
• Include configs/default.json in package metadata
• Avoid requiring Pillow unless GIF upload is actually used
• Prefer the RT100 screen/control HID endpoint when opening devices, with fallback to the previous
  behavior

Example

$ epomakercontroller list-temp-devices
DEVICE KEY CURRENT TEMPERATURE AUTO
coretemp-0 52.0°C *
coretemp-1 48.0°C
coretemp-2 49.0°C

$ epomakercontroller start-daemon --auto-temp

Testing

Tested locally on Arch Linux with an Epomaker RT100 Wired.

MPLBACKEND=Agg python -m pytest

Result:

26 passed, 2 warnings in 10.51s

Warnings observed:

• python-dateutil deprecation warning for utcfromtimestamp
• Matplotlib FigureCanvasAgg is non-interactive warning in tests/
  test_main.py::test_read_and_decode_bytes

Manual checks:

epomakercontroller send-time
epomakercontroller list-temp-devices
epomakercontroller start-daemon coretemp-0