add deepseek compatibility

feat: apply gemini cooldown to async model calls

feat: apply cooldown to bound model calls

feat: track batch rate limit window

feat: track per-question rate limit streaks

feat: abort batch on gemini daily quota

test: cover gemini cooldown lane behavior

feat: add gemini cooldown registry

feat: classify gemini client rate limits

feat: implement web search and file processing tools with robust retrieval fallbacks