fix: shelf reports double power

[rahulguptajss]

No description provided.

[Copilot]

Pull request overview

Adds a firmware-/module-aware correction for shelf PSU “power drawn” reporting, and uses that value as a fallback shelf power source when rail classification can’t reliably determine input/output rails.

Changes:

• Introduce pkg/power helpers to detect when psu-power-drawn must be divided by 8, and to track the minimum (oldest) module firmware version seen.
• Update both ZapiPerf and RestPerf disk plugins to (a) aggregate psu[-.]power_drawn across PSUs, (b) capture shelf module type + minimum module firmware, and (c) use PSU-reported power (with correction when needed) when rail classification is unavailable.
• Add unit tests for the new correction/version-min helpers.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
pkg/power/correction.go	Adds firmware/module-type based detection for divide-by-8 correction and a helper for selecting the minimum firmware version.
pkg/power/correction_test.go	Adds unit tests covering thresholds, case-insensitivity, invalid inputs, and version-min behavior.
cmd/collectors/zapiperf/plugins/disk/disk.go	Aggregates psu-power-drawn, captures module type + min module firmware, and falls back to corrected PSU power when rails can’t be classified.
cmd/collectors/restperf/plugins/disk/disk.go	Same as ZapiPerf path, using REST metric naming and rest shelf/module label sources.

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