sloproxy

fix(claude): emit message_delta when openai streaming finish reason is omitted master

- Ensure `message_delta` is emitted on tool call usage chunks and stream completion even if `finish_reason` is missing or null. - Add `terminalOpenAIFinishReason` fallback to map missing finish reasons to standard stop reasons. - Consolidate content block finalization into `finalizeOpenAIAnthropicContentBlocks` and delta emission into `emitAnthropicMessageDelta`. Closes: #5308


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2 changed files