Add Aurora Node Auditor to the exporters list

[auroraxo]

Adds Aurora Node Auditor to the Hardware related list, next to node_exporter, which is the section it is closest to: it exposes host vitals (CPU, memory, disk, load, process RSS) plus Raspberry Pi / edge sensor data (SoC temperature, WiFi RSSI, rpi_volt undervoltage alarm, decoded throttle flags, CPU frequency) read directly from /proc and /sys.

It is a zero-dependency Python 3.10+ stdlib daemon (no psutil, no shell-outs), Apache-2.0, 53 unit tests, installable as a wheel or as a multi-arch container image (linux/amd64, arm64, arm/v7 for 32-bit Pi). It is not intended to replace node_exporter on datacenter hosts — the niche is small/edge nodes and agent tooling that also want a structured JSON endpoint next to the Prometheus exposition.

Representative sample output, taken live from a running instance at https://codebyaurora.com/metrics:

# HELP node_uptime_seconds Total node uptime in seconds
# TYPE node_uptime_seconds gauge
node_uptime_seconds 825720.42
# HELP node_cpu_count Logical CPU count
# TYPE node_cpu_count gauge
node_cpu_count 4
# HELP node_memory_total_bytes Total physical memory in bytes
# TYPE node_memory_total_bytes gauge
node_memory_total_bytes 8326938624
# HELP node_memory_available_bytes Available physical memory in bytes
# TYPE node_memory_available_bytes gauge
node_memory_available_bytes 7289700352
# HELP node_disk_used_percent Disk usage percentage on root
# TYPE node_disk_used_percent gauge
node_disk_used_percent 17.73
# HELP process_rss_bytes Resident memory size of auditor process in bytes
# TYPE process_rss_bytes gauge
process_rss_bytes 25305088
# HELP process_threads Number of active threads in auditor process
# TYPE process_threads gauge
process_threads 1

The commit is signed off (DCO). Happy to move the entry to Miscellaneous instead if Hardware related is reserved for exporters that talk to dedicated hardware interfaces.