Add support for stable hwmon paths

[mkopec]

hwmon paths are unstable, they may change across reboots. instead, use stable paths like /sys/devices/platform/asus-ec-sensors/hwmon/hwmonX, where X stands for the allocated hwmon index.

[mkopec]

@claude pls handle this one

[claude]

Claude finished @mkopec's task in 2m 52s —— View job • claude/issue-6-20260320-1829 • Create PR ➔

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Working on Issue #6: Add support for stable hwmon paths

• Gather context and read codebase
• Understand current hwmon path handling
• Implement hwmon_resolve_path() utility (hwmon.c / hwmon.h)
• Update sensor_create and fan_create to resolve stable paths
• Update Makefile to include hwmon.c
• Update fand.conf example with stable path format
• Commit and push changes

Summary

Added stable hwmon path support via a new hwmon_resolve_path() function in hwmon.c/hwmon.h.

How it works: When a path's last component is exactly hwmon (e.g. /sys/devices/platform/asus-ec-sensors/hwmon), the function scans that directory at daemon startup to find the actual hwmonN child and returns its full path. Paths that already contain a concrete number (e.g. /sys/class/hwmon/hwmon7) are returned unchanged — full backward compatibility.

Config usage (new stable style):

sensors:
  - path: /sys/devices/platform/nzxt-kraken2/hwmon   # resolves to hwmon/hwmonX at startup
    index: 1

fans:
  - path: /sys/devices/platform/asus-ec-sensors/hwmon
    index: 1

Files changed: hwmon.c (new), hwmon.h (new), sensor.c, fan.c, Makefile, fand.conf