platform/webui: fold confidential-computing into a GPU config + NVLink check

The standalone "confidential-computing" SAT target only ever checked CC
readiness, which most fleets never opt into (a NOT_READY verdict there
isn't a fault). Meanwhile DCGM diag never asserts GPU config compliance
(ECC/MIG/power-limit vs factory default) or NVLink topology (per NVIDIA's
own DGX BasePOD deployment guide, this needs a separate validation step)
— gaps confirmed against public DCGM docs and a real NV17-vs-expected-NV18
bonded pair found on a live bundle.

Repurposes the routine into "nvidia-config": reuses the existing
ListNvidiaGPUSettings() (already backing the GPU-settings page) to flag
ECC disabled, a MIG mode change stuck pending a reset/reboot, and a power
limit capped >5% below default; parses "nvidia-smi topo -m" bonded pairs
against "nvlink -s/-e" to flag any inactive lane or nonzero replay/
recovery/CRC counter on an otherwise-active bond. CC readiness is folded
in as one informational field (does not gate overall_status) rather than
a dedicated test. Reports under the same pcie:gpu:nvidia severity key as
every other nvidia-* SAT target instead of an isolated key, so a
config/NVLink FAILED result isn't invisible next to stress-test results.

Also fixes ApplySATResultToDB silently dropping any target with no
matching switch case (exactly what the old confidential-computing target
did) with a new coverage test enumerating every real SAT target.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

audit/internal/platform/nvidia_settings.go

@@ -70,7 +70,7 @@ func (s *System) ListNvidiaGPUSettings() ([]NvidiaGPUSetting, error) {
 
 // queryNvidiaGPUCCState reads the per-GPU Confidential Computing state via
 // `nvidia-smi conf-compute -i <index> -q`, reusing the same field-name
-// convention as RunConfidentialComputingCheckPack's parseConfComputeFields.
+// convention as RunNvidiaConfigCheckPack's parseConfComputeFields.
 // Returns "" if the driver/GPU doesn't support conf-compute at all.
 func (s *System) queryNvidiaGPUCCState(index int) string {
 	out, err := satExecCommand("nvidia-smi", "conf-compute", "-i", strconv.Itoa(index), "-q").Output()