OpenWrt agent: add temperature sensors and harden wireless SNMP setup

[perceival]

This change is adding temperature sensors and improving (creating automation) in SNMP setup for WiFi sensors. Dependent on librenms/librenms#19347 (recreated after botched previous PR - #595).

Notes for reviewers:

wlInterfaces.sh

Replaces static interface mapping with live discovery from hostapd/iwinfo.
Filters inactive/placeholder VAPs and prefers active hostapd-managed interfaces.
Produces stable labels and handles duplicate SSIDs by appending band suffixes (24/5/6).
Keeps fallback logic for systems without full hostapd metadata.
wlClients.sh

Moves from simple station-dump counting to MAC-based counting with dedupe.
Supports both per-interface and aggregate modes.
Uses hostapd get_clients when available, with iwinfo fallback.
Deduplicates MLO/MLD-related addresses in aggregate mode to avoid overcounting.
wlRate.sh, wlNoiseFloor.sh, wlSNR.sh, wlFrequency.sh

Adds fallback parsing paths for client-mode interfaces where assoclist can be empty.
Normalizes output for SNMP extend compatibility (first line numeric value, optional second context line).
setup-snmpd.sh and snmpd-config-generator.sh

Introduces install/apply workflow for OpenWrt helper scripts.
Ensures managed LibreNMS blocks are replaced cleanly instead of duplicated.
Supports non-interactive apply (-y) and optional no-restart (--no-restart).
lm-sensors-pass.sh

Adds pass script implementing LM-SENSORS-MIB subtree behavior for thermal zones.
Handles both GET and GETNEXT traversal semantics for SNMP requests.
Scope check

PR remains constrained to OpenWrt integration paths with one upstream-based commit and the expected 12-file diff.

@VVelox I have recreated the PR from the scratch including your requested changes. Kindly please review.

[perceival]

@VVelox could you please take a look...?

[perceival]

Updated the net-snmp OpenWrt integration: the distro extend now uses /etc/os-release for improved detection, and the unused snmpd-base-config file has been removed.
@VVelox kindly please review.

[perceival]

Opened #618 to give this broader visibility and track the feature request separately from the implementation. The PR remains ready for review.

[perceival]

@VVelox could you...?

[sshockley]

For what it's worth I'm testing this now and it's working well.

[perceival]

Friendly bump @VVelox — @sshockley's report above ("testing this now and it's working well") confirms the agent works in a second OpenWrt environment beyond my own. PR is mergeable, no conflicts, CLA signed. Could you take a look when you have a minute? Happy to address any review feedback.