Set created_at on the benchmark records

2026-09-07T11:39:36Z - the time the measurements were sent over (12:39:36 BST).

context.dataset (name + sample_count) is still outstanding and remains the only schema validation error. Note dataset.name forms part of the report identity URN, so it should not be filled with a placeholder: a later correction would insert a duplicate report rather than update the existing one. created_at is not part of that URN, so this value can be corrected in place if the true measurement time differs.

benchmarks/gemma-4-e2b-vivo-x300-bf16.yaml

@@ -1,5 +1,6 @@
 version: 1.2.0
 report_type: llm-generative
+created_at: '2026-09-07T11:39:36Z'
 profile: Baseline
 context:
   target_ref: vivo-x300

benchmarks/gemma-4-e2b-vivo-x300-int4.yaml

@@ -1,5 +1,6 @@
 version: 1.2.0
 report_type: llm-generative
+created_at: '2026-09-07T11:39:36Z'
 profile: Arm-Optimized
 context:
   target_ref: vivo-x300