feat(evidence): add NIM support to evidence collection and restructure conformance docs

[yuanchen8911]

Summary

• Add NIM inference and NIM Operator paths to evidence collection script
• Restructure conformance docs to v1.35/nim-eks/ (mirrors CNCF submission repo)
• Update all docs for NIM on EKS as the certified product

Changes

Evidence collection (pkg/evidence/scripts/collect-evidence.sh):

• Add collect_service_metrics_nim() — creates ServiceMonitor, sends inference requests, waits for Prometheus to scrape with health: up, captures metrics from both NIM /v1/metrics endpoint and Prometheus queries
• Add collect_operator_nim() — validates NIM Operator deployment, CRDs (apps.nvidia.com), webhooks (namespace-based lookup), NIMService reconciliation, webhook rejection test
• Detection priority: Dynamo > NIM Operator > Kubeflow Trainer (for both metrics and operator checks)

Documentation restructure:

• Move from evidence/ + submission/ to v1.35/nim-eks/ structure (mirrors cncf/k8s-ai-conformance/v1.35/<product>/)
• Supports future submissions (e.g., v1.35/nim-gke/, v1.36/nim-eks/)
• Update all internal links and PRODUCT.yaml evidence URLs

PRODUCT.yaml updates:

• platformName: "NVIDIA NIM on EKS"
• websiteUrl: developer.nvidia.com/nim
• repoUrl: github.com/NVIDIA/k8s-nim-operator
• documentationUrl: NIM Helm deploy docs
• NIM-specific notes for ai_service_metrics and robust_controller requirements

Test plan

• Evidence collection produces 9/9 PASS on EKS with NIM workload
• AI Service Metrics: Prometheus discovers NIM target with health: up via ServiceMonitor
• Robust Operator: NIM Operator webhooks found, NIMService reconciled, rejection test passes
• All links verified (README → evidence/, PRODUCT.yaml → full GitHub URLs)
• No stale references to old evidence/ or submission/ paths

Depends on #478

[dims]

LGTM