Refactor ASRClient to delegate to provider (DashScopeASRProvider or OpenRouterASRProvider) via create_asr_provider() factory. transcribe_full() now async. Move _to_traditional to asr_providers.py (re-exported from asr_client.py for backward compat). Update video.py router to await transcribe_full() and validate API key per provider (DASHSCOPE_API_KEY for dashscope, OPENROUTER_API_KEY for openrouter).
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>