fix: load partial transcription to trajectory in Live API ADK evaluation

[wzhang2705]

feat: Preserve transcription event order in conversation trajectory

• Add agent_name parameter to _run_live_inference_loop
• Yield synthetic text events inline when partial transcriptions arrive
• Remove post-loop transcription accumulation logic

Testing Plan

Unit Tests:

• Added test_generate_inferences_live_with_synthetic_events in test_evaluation_generator.py

[adk-bot]

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