Merge origin/main into contrib/routed-codex-model-catalog.
Single conflict in openai_gateway_forward.go: main added
ClearActualOpenAIUpstreamEndpoint + SetActualOpenAIUpstreamEndpoint
(commit 4795650d2) at the same insertion point where the PR added
filterOpenAIResponsesNoneReasoningEffortForAccount. Both changes
are independent — endpoint observability first, then body filtering.