Add per-precision benchmark phases, weighted TOPS scoring, and ECC tracking

- Split steady window into 6 equal slots: fp8/fp16/fp32/fp64/fp4 + combined
- Each precision phase runs bee-gpu-burn with --precision filter so PowerCVPct reflects single-kernel stability (not round-robin artifact)
- Add fp4 support in bee-gpu-stress.c for Blackwell (cc>=100) via existing CUDA_R_4F_E2M1 guard
- Weighted TOPS: fp64×2.0, fp32×1.0, fp16×0.5, fp8×0.25, fp4×0.125
- SyntheticScore = sum of weighted TOPS from per-precision phases
- MixedScore = sum from combined phase; MixedEfficiency = Mixed/Synthetic
- ComputeScore = SyntheticScore × (1 + MixedEfficiency × 0.3)
- ECC volatile counters sampled before/after each phase and overall
- DegradationReasons: ecc_uncorrected_errors, ecc_corrected_errors
- Report: per-precision stability table with ECC columns, methodology section
- Ramp-up history table redesign: GPU indices as columns, runs as rows

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

audit/internal/webui/api.go

@@ -497,6 +497,7 @@ func (h *handler) handleAPISATRun(target string) http.HandlerFunc {
 				GPUIndices         []int    `json:"gpu_indices"`
 				ExcludeGPUIndices  []int    `json:"exclude_gpu_indices"`
 				StaggerGPUStart    bool     `json:"stagger_gpu_start"`
+				ParallelGPUs       bool     `json:"parallel_gpus"`
 				Loader             string   `json:"loader"`
 			Profile            string   `json:"profile"`
 			DisplayName        string   `json:"display_name"`
@@ -519,6 +520,7 @@ func (h *handler) handleAPISATRun(target string) http.HandlerFunc {
 				GPUIndices:         body.GPUIndices,
 				ExcludeGPUIndices:  body.ExcludeGPUIndices,
 				StaggerGPUStart:    body.StaggerGPUStart,
+				ParallelGPUs:       body.ParallelGPUs,
 				Loader:             body.Loader,
 			BurnProfile:        body.Profile,
 			DisplayName:        body.DisplayName,